Answer:
The valency of calcium is +2
Explanation:
Calcium is in group two. The members of group two are divalent metals that loose two electrons to form M^2+.
Since they form M^2+, they form ionic bonds with two uninegative ions. Chlorine is in group 17. This implies that its valency is -1 and it accepts one electron when it participates in an ionic bond.
Hence it will take two chlorine atoms to receive two electrons from one calcium atom in an ionic bond making the ratio of calcium to chlorine in the compound 2:1.
An element’s most stable ion forms an ionic compound with bromine, having the formula XBr2. If the ion of element "X" has a mass number of 230 and has 86 electrons, what is the identity of the element, and how many neutrons does it have?
Answer:
88
Explanation:
The ion has a charge of 2+, therefore the number of neutrons it possess is 86+2
which equals 88
The element X having a mass number of 230 and has 86 electrons is radium and has 142 neutrons.
An atom is composed basically of electrons, protons and neutrons. In a neutral atom, the number of protons and electrons are equal. The number of neutrons is the difference between the mass number and the number of protons (atomic number).
Since we know that the ion of the element X has 86 electrons and the compound formed is XBr2, it then means that neutral X has 88 electrons.
The number of electrons in the neutral atom is the same as the number of protons or atomic number. An element can be identified by its atomic number. The element having atomic number 88 is radium.
The number of neutrons is obtained as;
Mass number - atomic number
230 - 88 = 142 neutrons
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Levi decides to examine the effect of fertilizer on the growth of tomato plants. He chooses four plants for his experiment and applies varying amounts of fertilizer to three of them. He does not apply fertilizer to one plant. Over a 15-day period, the plants receive fertilizer on Days 1, 4, 7, 10, and 13. Levi measures the height of all of his plants with a meter stick on days 3, 6, 9, 12, and 15. He also makes sure to hold all experimental factors constant except for the fertilizer.
Where should the independent and dependent variables of Levi's experiment be placed when graphed?
Select all that apply.
the amount of fertilizer;y-axis
plant height;x-axis
the amount of fertilizer;x-axis
plant height; y-axis
Answer:
the amount of fertilizer; x-axis
plant height; y-axis
Explanation:
The independent and dependent variables of Levi's experiment placed when graphed are the amount of fertilizer and the y-axis. Option B is correct.
What are independent and dependent variables?The independent variables are those which are not dependent on other factors for their working or cannot be influenced by any other factor and the dependent variable is just the opposite of this one.
The experiment depends on the height of the plant but the fertilizer is independent of to work of the plant and fertilizer is independent and high and depends on other factors.
Therefore, Option B is correct. independent and dependent variables of Levi's experiment placed when graphed are the amount of fertilizer and the y-axis.
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anyone knows how to do this-
Explanation:
The number of protons in the element C^12 (Carbon) is 6, number of electrons 12 and number of Neutrons is 6, same as the number of protons it contains
C^13 has 13 electrons, 6 protons and 7 Neutrons this one's neutron number is different from proton number because it's an isotope
Na^-1 has gained an electron so the number of electrons it has = 24 and the number of protons shown as 11 which means there are 23 - 11 = 12 Neutrons
O^-2 has gained two electrons and got 18 electrons in total, 8 protons and 8 neutrons
HELP!!!!!!, I need this urgently!!!
Compare the properties of producer and water gas
Answer:
Producer gas and water gas contain carbon monoxide and hydrogen.
If an object's mass is 70 g, and its volume is 10cm cubed, what is its density?
If an object's mass is 70 g, and its volume is 10cm cubed, its density is 7 centimeter cube.
What is density?The density of any solid substance is the unit of the area occupied by it in per centimeter of the cube of the volume in the given sample and calculated by dividing the mass and the volume of the compound unit will be centimeter cube.
The mass of the given object is 70 gram and the volume is given is 10 cm to find the density,
Density = mass of object / volume of object
substituting the value in the formula,
Density = 70 / 10
Density = 7 centimeter cube.
Therefore, the density of the given object will be 7 centimeter cube if an object's mass is 70 g, and its volume is 10cm cubed.
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Please help me...
Atoms of elements X, Y and Z have 16, 17 and 19 electrons, respectively. Atoms of argon have 18 electrons.
a Determine the formulae of the compounds formed by the combination of the atoms of the elements:
(i) X and Z
(ii) Y and Z
(iii) X with itself.
b In each of the cases shown in
A (i)–(iii) above, name the type of chemical bond formed.
c Give two properties you would expect to be shown by the compounds formed in an (ii) and an (iii).
Answer:
a 1) XZ2
2) YZ
3) X2
b 1) Ionic bond
2) Ionic bond
3) covalent bond
c) ionic compounds has high melting and boiling point
ionic compounds can conduct electicity in aqueous form
covalent compounds have electrons shared between the atoms
covalent compounds have lower melting point compared to ionic compound
Answer:
(i) XZ = Potassium Sulfide [K2SO4]
(ii) YZ = Potassium Chloride [KCI]
(iii) X = Sulfur [S]
b) (i) Ionic Bond. (ii) Ionic Bond. (iii) Covalent Bond.
c) (i) Ionic compounds have high melting and boiling points.
(ii) Ionic compounds can conduct electricity in a molten state or a solution as they have ions that can move and carry charge.
(iii) Covalent compounds have low melting and boiling points.
(iv) Covalent compounds can not conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge.
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What is Mendeleev’s Periodic Law? How many elements were classified by Mendeleev?
Answer:
1.the law that the properties of the elements are periodic functions of their atomic numbers. Also called Mendeleev's law. (originally) the statement that the chemical and physical properties of the elements recur periodically when the elements are arranged in the order of their atomic weights.
Explanation:
2.Mendeleev’s Periodic Law states that the properties of elements are the periodic function of their relative atomic masses. Mendeleev arranged all 63 elements; which were discovered till his time; in the order of their increasing relative atomic masses in a tabular form. It is known as Mendeleev’s Periodic Table.
What would be the pH of an HNO3 solution if the [H+] = 3.26 x 10-6 moles/liter? 5.49 4.67 6.32
Answer:
5.49
Explanation:
pH = - log[3.26 x 10-6] =5.49
What combination of substances will give a buffered solution that has a pH of 5.05? (Assume each pair of substances is dissolved in 5.0 L of water.) (Kb for NH3 = 1.8 ´ 10–5; Kb for C5H5N = 1.7 ´ 10–9) Select one: a. 1.0 mole NH3 and 1.5 mole NH4Cl b. 1.5 mole NH3 and 1.0 mole NH4Cl c. 1.0 mole C5H5N and 1.5 mole C5H5NHCl d. 1.5 mole C5H5N and 1.0 mole C5H5NHCl e. none of these
Answer:
c. 1.0 mole C5H5N and 1.5 mole C5H5NHCl
Explanation:
We can determine pH of a buffer using H-H equation:
pH = pKa + log [A⁻] / [HA]
Where [A⁻] is concentration of conjugate base and [HA] concentration of weak acid. These concentrations can be computed as moles of each species.
We need to determine pKa of both NH₃ and C₅H₅N buffers, thus:
pKb = -log Kb
NH₃ pKb = -log 1.8x10⁻⁵ = 4.74
C₅H₅N pKb = -log 1.7x10⁻⁹ = 8.77
And pKa = 14 - pKb:
NH₃ pKa = 14 - 4.74 = 9.26
C₅H₅N pKb = 14 - 8.77 = 5.23
A buffer works only under pH's between pKa-1 and pKa + 1. As pKa NH₃ buffer is 9.23 is not possible to produce a buffer with pH 5.05 for this system.
Thus, we only will compute the buffers made with C₅H₅N:
c. 1.0 mole C5H5N (Weak base) and 1.5 mole C5H5NHCl (Conjugate acid)
pH = pKa + log [A⁻] / [HA]
pH = 5.23+ log [1.0 moles] / 1.5 moles]
pH = 5.05d. 1.5 mole C5H5N and 1.0 mole C5H5NHCl
pH = pKa + log [A⁻] / [HA]
pH = 5.23+ log [1.5 moles] / 1.0 moles]
pH = 5.41Right solution is:
c. 1.0 mole C5H5N and 1.5 mole C5H5NHClWhich bond type is found in ammonium chloride. Select one: a. metallic b. covalent c. ionic
Answer:
ionic
Explanation:
In NH4Cl molecule, ionic bond is formed between NH4+ and Cl– ions, 3 covalent bonds are formed between N and three H atoms and one coordinate bond is formed between N and 1 H atom.
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Answer:
[tex]\boxed{\sf c. \ ionic}[/tex]
Explanation:
NH₄Cl is formed by an ionic bond between NH₄⁺ and Cl⁻ ions.
NH₄Cl (solid) ⇒ NH4⁺ (aqueous) + Cl⁻ (aqueous)
In the molecule 4H2O2 the number of hydrogen atoms is what
Answer:
Scientists
Explanation:
Scientists because they are the one who makes hypothesis.
If a gas displays a solubility of 0.00290M at a partial pressure of 125 kPa, what is the proportionality constant for this gas in this solvent and at this temperature?
Answer:
The proportionality constant ( Henry’s constant) = 2.32 * 10^-5 M/kPa
Explanation:
Here in this question, we are concerned with calculating the proportionality constant for this gas.
Mathematically, we can get this from Henry law
From Henry law;
Concentration = Henry constant * partial pressure
Thus Henry constant = concentration/partial pressure
Henry constant = 0.00290 M/125 kPa = 2.32 * 10^-5 M/kPa
the overall take away of an experiment’s results is the______. A. hypothesis B. introduction C. conclusion
Answer:
conclusion
Explanation:
it can't be a hypothesis since tests are carried out to verify so it is not a theory
an introduction to an experiment only gives the basis of what we are investigating therefore nothing has been proven and the question is still unanswered
The overall takeaway of an experiment’s results is the conclusion. Hence, option C is correct.
What is a hypothesis?A hypothesis is a testable statement about the relationship between two or more variables or a proposed explanation for some observed experiment.
The overall takeaway of an experiment’s results can't be a hypothesis since tests are carried out to verify so it is not a theory
An experiment only gives an idea about the investigation therefore nothing has been proven and the question is still unanswered.
Hence, the overall takeaway of an experiment’s results is the conclusion.
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Was is meant by the term suprenatural? Does science deal with the supernatural?
A. The term supernatural literally means (within nature) Science deals with the supernatural because it works within nature, not above it
B. The term supernatural literally means (above nature) Science does not deal with the supernatural because it works within nature, not above it
C. The term supernatural literally means (within nature) Science does not deal with the supernatural because it works above nature, not within it
D. The term supernatural literally means (above nature) Science deals with the supernatural because it also works with nature, not within it
Answer:
it's option D
If you are designing an experiment, how will you determine your independent or dependent variable?
Answer:
The independent variable effects the dependent variable.
Explanation:
The independent variable Is what you change whereas the dependent variable would change because of that.
for example, the indipendent variable could be how much you water a plant in ml each day, and the dependent variable would be how tall each plant grown]s with that water doseage per day.
List the metals Mg, Cu, Au, Na and Al in the decreasing order of their reactivity with air.
Answer:
Na is most reactiveAlcuAu is less reactiveIN HEREAnswer:
Potassium (K)
Sodium (Na)
Calcium (Ca)
Magnesium (Mg)
Aluminium (Al)
Iron (Fe)
Lead (Pb)
Copper (Cu)
Silver (Ag)
Gold (Au)
HELPPPP Name the three states of matter. Describe the arrangement and movement of atoms in a substance for each state.
Solid, Liquid, and Gas
Solid is the state in which matter maintains a fixed volume and shape; liquid is the state in which matter adapts to the shape of its container but varies only slightly in volume; and gas is the state in which matter expands to occupy the volume and shape of its container.
The states of matter are solid, liquid, and gas. Solid is the state in which matter maintains a fixed volume and shape; liquid is the state in which matter adjusts to the shape of its container but tends to vary only mildly in volume; and gas is the state in which matter expands to occupy the volume and shape of its container.
What is matter?Matter would be any substance with mass and volume that occupies space.
Matter exists in three states: solid, liquid, and gas. The states of matter are solid, liquid, and gas.
Solid is the phase in which matter retains a fixed volume and shape.Liquid is the entity in which matter adjusts to the shape of its container but tends to vary only slightly in volume.Gas is the phase in which matter expands to occupy the volume and shape of its container.Thus, above-mentioned are the three states of matter.
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Ytu perform an electrolysis reaction using FeCl, iron (1) chloride. Which of the following will happen?
A. Chlorine will move to the positive electrode and become reduced.
B. Iron will move to the positive electrode and become oxidized.
C. Chlorine will move to the negative electrode and become oxidized.
D. Iron will move to the negative electrode and become reduced.
Answer:
The answer is "Option B"
Explanation:
when we react with FeCl, iron, and chloride to both the electrolysis. So, iron is charged positive ion, as well as passes to the negative, is cathode electrode. But there is a decrease in the cathode.
The equation can be defined as follows:
[tex]FeCl_2[/tex] [tex]\longrightarrow[/tex][tex]Fe + Cl_2[/tex]
In the above equation, when the iron chloride electrolysis solution, it will give the iron(II) and the chlorine. This process happens when the hydrogen chloride solution at a temperature of about 90 ° C.
Answer: D
Explanation: As Fe is positive charged while chlorine is negative charged.
(D) is correct. As iron moves to negative and it get reduce as negative electrode is cathode
Propane (C3H8), a common fuel, reacts with oxygen to form carbon dioxide and water according to the equation below: C3H8 + 5O2 → 3CO2 + 4H2O If a propane heater burns 38.95 g C3H8, it consumes
Answer:
0.8833 mole of C3H8
Explanation:
Given:
Mass of C₃H₈ (Propane) = 38.95 gram
Computation:
Molar mass of C = 12.01
Molar mass of H = 1.008
Molar mass of C₃H₈ (Propane) = 3(12.01) + 8(1.008)
Molar mass of C₃H₈ (Propane) = 36.03 + 8.064
Molar mass of C₃H₈ (Propane) = 44.094
Number of mol in 38.95 gram Propane = Mass / Molar mass
Number of mol in 38.95 gram Propane = 38.95 / 44.094
Number of mol in 38.95 gram Propane = 0.88334
Answer:
Use the Periodic Table to find molar masses.
Propane (C3H8), a common fuel, reacts with oxygen to form carbon dioxide and water according to the equation below:
C3H8 + 5O2 → 3CO2 + 4H2O
If a propane heater burns 38.95 g C3H8, it consumes
38.95 mol C3H8.
0.8830 mol C3H8.
1 mol C3H8.
44.10 mol C3H8.
Part 2
How many moles of oxygen are required to produce 37.15 g CO2?
37.15 g CO2 = 1.407 mol O2
Part 3
What mass of propane is necessary to react with the amount of oxygen calculated in the previous question?
12.41 g C3H8
A balloon is floating around outside your window. The temperature outside is 31 ∘C , and the air pressure is 0.700 atm . Your neighbor, who released the balloon, tells you that he filled it with 4.10 moles of gas. What is the volume of gas inside this balloon? Express to THREE signficant figures.
Answer:
the volume of gas inside this balloon = 146.3 L
Explanation:
Given that:
The temperature T = 31 °C = ( 31 + 273.15 )K = 304.15 K
The air pressure P = 0.700 atm
number of moles of gas n = 4.10 moles
Gas constant = 0.0821 L atm/K/mol
The objective is to calculate the volume of the gas inside the ballon.
Using the Ideal gas equation
PV = nRT
V = nRT/P
V = (4.10×0.0821×304.15)/0.700
V = 102.3799/0.700
V = 146.257 L
V = 146.3 L
Thus, the volume of gas inside this balloon = 146.3 L
4 examples of ionic bonding identifying in each one the anion, the cation and demonstrate the ionic bonding by means of the electronegativity difference.
Answer:
Here are some examples
Explanation:
NaCl
Cation = Na⁺, Anion = Cl⁻; ΔEN = |0.93 - 3.16| = 2.23
MgS
Cation = Mg²⁺, Anion = O²⁻; ΔEN = |1.31 - 3.44| = 2.53
KBr
Cation = K⁺, Anion = Br⁻; ΔEN = |0.82 - 2.96| = 2.14
CaF₂
Cation = Ca²⁺, Anion = F⁻; ΔEN = |1.00 - 3.98| = 2.98
In each case, ΔEN > 1.6, so the compound is ionic.
3.7500 x 104 + 9.7100 x 105
Answer: [tex]1409.55[/tex]
Remove the 0's from each decimal number
[tex]3.7500 ---> 3.75\\9.7100 ---> 9.71[/tex]
Multiply
[tex]3.75*104=390\\9.71*105=1019.55[/tex]
Add
[tex]930+1019.55=1409.55[/tex]
I'll GIVE BRAINLIEST: In a redox reaction, CO is changed to CO2. How many electrons must be lost or gained by C and why?
Answer:
C is gaining 2 electrons
Explanation:
O has a 2- charge so for CO to pick up another O atom would add 2 more electrons.
Answer:
C gains 2 electrons
Explanation:
In the redox reaction, CO is changed into CO2 which means there is an additional oxygen. Oxygen loses 2 of its electrons in order to neutralize. So, C must be gaining 2 electrons in order to make the bond.
Explain how the energy of a toy car is transformed as it slides down a ramp. Give evidence that the energy of the car remains the same at all points on the ramp. (30 points)
Answer:
As the car starts to slide down the ramp, it is kinetic energy and when it's on the top of the ramp, it is potential energy. We can see that the energy is now being transferred through the car and ramp.
tion 1/3
A white rhinoceros weighs about 1,500 pounds (lb). How many tons (T) does the rhinoceros weigh? (1 T =
A. 1.5 T
o
B. 1 T
C. 0.75 T
D. 0.5 T
Answer:
.75 Tons
Explanation:
1 Ton is equal to 2,000 pounds
A star is estimated to have a mass of 2.0 x 10 ^36kg. Assuming it to be a sphere of average radius of 7.0 x 10 ^5 km. Calculate the average density of the star in g/cm^3 and in lb/ft^3
Answer:
a) 1.392 x 10^6 g/cm^3
b) 8.69 x 10^7 lb/ft^3
Explanation:
mass of the star m = 2.0 x 10^36 kg
radius of the star (assumed to be spherical) r = 7.0 x 10^5 km = 7.0 x 10^8 m
The density of substance ρ = mass/volume
The volume of the star = volume of a sphere = [tex]\frac{4}{3}\pi r^{3}[/tex]
==> V = [tex]\frac{4}{3}*3.142*(7.0*10^8)^{3}[/tex] = 1.437 x 10^27 m^3
density of the star ρ = (2.0 x 10^36)/(1.437 x 10^27) = 1.392 x 10^9 kg/m^3
in g/cm^3 = (1.392 x 10^9)/1000 = 1.392 x 10^6 g/cm^3
in lb/ft^3 = (1.392 x 10^9)/16.018 = 8.69 x 10^7 lb/ft^3
how many oxygen atoms are in 7.25g of calcium nitrate
Answer:
The answer to this question is approximately equal to 1.6 ×
[tex] 1.6 \times {10}^{23} atom \: o[/tex]
calculate the weight of 3.491 into 10 to the power 19 molecules of cl2
Answer:
The mass of 3.491 × 10¹⁹ molecules of Cl₂ of Cl₂ is 4.11 × 10⁻³ grams
Explanation:
The number of particles in one mole of a substance id=s given by the Avogadro's number which is approximately 6.023 × 10²³ particles
Therefore, we have;
One mole of Cl₂ gas, which is a compound, contains 6.023 × 10²³ individual molecules of Cl₂
3.491 × 10¹⁹ molecules of Cl₂ is equivalent to (3.491 × 10¹⁹)/(6.023 × 10²³) = 5.796 × 10⁻⁵ moles of Cl₂
The mass of one mole of Cl₂ = 70.906 g/mol
The mass of 5.796 × 10⁻⁵ moles of Cl₂ = 70.906 × 5.796 × 10^(-5) = 4.11 × 10⁻³ grams
Therefore;
The mass of 3.491 × 10¹⁹ molecules of Cl₂ of Cl₂ = 4.11 × 10⁻³ grams.
calculate the pH of 500cm3 of 0.2mol/dm3 Ca(OH2), assume complete ionisation
Answer:
The pH of 500 cm³, 0.2 mol/dm³, Ca(OH₂) is ≈ 13.6
Explanation:
The given parameters are;
Concentration of the calcium hydroxide, Ca(OH₂) = 0.2 mol/dm³
Volume of the calcium hydroxide, Ca(OH₂) = 500 cm³
Given that the calcium hydroxide, Ca(OH₂), undergoes complete ionization in water, complete dissociation, we have;
Ca(OH₂) ⇄ Ca²⁺ + 2 OH⁻
Therefore, we have;
2 moles of [OH⁻] for each mole of Ca(OH₂) which gives the concentration of [OH⁻] as
[OH⁻] = 2 × 0.2 ≈ 0.4 mol/dm³
The pH is given by the formula
pH = 14 + ㏒₁₀ [OH⁻]
pH = 14 + ㏒₁₀ (0.4) = 14 - 0.3979 = 13.6021 ≈ 13.6
The pH of the 500 cm³ 0.2 mol/dm³ Ca(OH₂) ≈ 13.6.
Explain the different between a molecule and a compound.
Answer:
-A molecule is the smallesr part is compound whereas a compound is the combination of two or more atoms in a fixed proportion by wiehgt.
- A glass of water is an example of compound but a small portion of water can be called molecule.
