Which of the following statements is true? A. Isotopes of the same element have the same number of protons and neutrons. B. Isotopes have the same physical properties as the normal atom but different chemical properties. C. Isotopes have the same chemical properties as the normal atom but different physical properties. D. If an isotope of one element has the same atomic mass as another element, they will have the same properties.

Answer:

[tex]\boxed{\sf{view \ explanation}}[/tex]

Explanation:

Compound definition:

A compound is a chemical substance formed by two or more chemically bonded elements.

Three compounds:

Water is a compound with the formula [tex]\sf H_2O[/tex].

Two hydrogen atoms and one oxygen atom is present in one molecule of water.

Sodium chloride or table salt is a compound with the formula [tex]\sf NaCl[/tex].

One sodium atom and one chlorine atom is present in one molecule of sodium chloride.

Ammonia is a compound with the formula [tex]\sf NH_3[/tex].

In one molecule of ammonia, one nitrogen atom and three hydrogen atoms are present.

Answer:

See below

Explanation:

Three compounds are:

1) [tex]\mathrm {H_{2}SO{4}}[/tex] [Sulfuric acid]

The elements in this compound are hydrogen (H) , Sulfur (S) and Oxygen (O).

2) [tex]\mathrm {NaOH}[/tex] [Sodium hydroxide]

The elements in this compound are Sodium (Na) , Oxygen (O) and Hydrogen (H).

3) [tex]\mathrm {HCl}[/tex] [Hydrochloric acid]

The elements are Hydrogen (H) and Chlorine (Cl).

Explanation:

A scientific idea is an explanation for how something works, or the truth about some aspect of the world, that was figured out using the scientific process. ... Scientific ideas change over time as the evidence improves. The more experiments they do , and the more data they collect, the better the scientific ideas become.

Answer:

[tex]\huge\boxed{King\ of \ Acid}[/tex]

Explanation:

H2SO4 (also called sulfuric acid) is also called King of Acids. It is a highly reactive acid.

Answer:

[tex]\large \boxed{\mathrm{a. \ king \ of \ acid }}[/tex]

Explanation:

[tex]\sf H_2SO_4[/tex] or sulfuric acid is known as the king of acid. It is a very reactive acid and is a strong acid in general.

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.

Answer:

true

Explanation:

The standard laboratory rule is to always add acids or bases to solvent and not the other way round.

The dissolution of concentrated acids/bases in solvents (water) generates heat energy. Thus, if the solvent is added to them, a layer of hot weak acid or base will be formed and this will boil and spray around, causing an explosion.

On the other hand, if acid/base is added to solvents, they flow into the solvents and get diluted immediately without any boiling taking place. Hence, it is safe to add acid/base to solvents and not the other way round.

Answer:

A) The amount in grams of Li₃N produced is 1.243 g

B) N₂, is the limiting reagent

The mass of the non-limiting reagent, Li, remaining after the reaction is completed is 1.757 g

Explanation:

The given parameters are;

The mass of Li(s) = 2.5 grams

The mass of N₂ (g) = 0.5 grams

The chemical equation for the reaction can be presented as follows;

6 Li (s) + N₂ (g) → 2 Li₃N

Therefore, 6 moles of Li reacts with 1 mole of N₂  to produce 2 moles of Li₃N

The molar mass of Li = 6.941 g/mol

The molar mass of N₂ = 28.0134 g/mol

The number of moles of a reactant or product, n is given by the relation;

n = Mass of substance/(Molar mass of the substance)

For lithium, Li, n = 2.5/6.941 = 0.3602 moles

For Nitrogen gas, N₂, n = 0.5/28.0134  = 0.01785 moles

A) Given that 1 mole of  N₂ to produces 2 moles of Li₃N

0.01785  moles of  N₂ will produces 2×0.01785 = 0.0357 moles of Li₃N

The molar mass of Li₃N = 34.83 g/mol

The mass of Li₃N = 34.83 g/mol × 0.0357 moles = 1.243 g

B) 6  moles of Li reacts with 1 mole of N₂ to produce 2 moles of Li₃N

0.3602 moles will reacts with 1/6×0.3602 = 0.06003 mole of N₂

Therefore, N₂, is the limiting reagent and we have;

0.01785  moles of  N₂ will react with 6×0.01785 = 0.1071  moles of Li

The number of of moles of Li left = 0.3602 - 0.1071 =0.2531 moles

The mass of lithium left = 0.2531 moles × 6.941 g/mol = 1.757 g

The mass of lithium remaining after the reaction is completed = 1.757 g.

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)

Answer:

Ingredients OR tenderising

Explanation:

Answer:

The answer is the same as .

Explanation:

There are 3 atoms in NaOH, 1 sodium, 1 oxygen and 1 hydrogen.

There are 3 atoms in H2O, 2 hydrogen and 1 oxygen.

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.

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.

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

Answer:

ripple marks

Explanation:

Undulation is defined as the to and fro wavelike motion in a fluid or elastic medium.

Undulation in sandy material is called ripple marks because ripple marks are the sediments of rocks that show wavy structure at its surface due to agitation by water and wind.

Hence, the correct answer is "ripple marks".

Answer:

Scientists

Explanation:

Scientists because they are the one who makes hypothesis.

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.

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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Answer:

The body stores lipids ingested as fat and uses this energy when needed-chemical energy

A person's hat falls off and lands on the ground- gravitational energy

A wave of water pushes a surfer to shore- mechanical energy

A burner on a stove heats up a tea kettle- thermal energy

A power plant splits atoms to generate power for a city- nuclear energy

A nerve sends an impulse to another nerve- electrical energy

A plant absorbs the Sun's rays to start the process of photosynthesis- radiant energy

Explanation:

Gravitational energy is energy stored by an object as a consequence of its height.

Mechanical energy is the energy that is possessed by an object due to its motion or due to its position.

Chemical energy refers to energy stored in chemical bonds in a substance.

Thermal energy is a form of energy that exists due to temperature difference between two bodies.

Nuclear energy refers to energy stored in the nucleus of an atom.

Electrical energy is a form of energy resulting from the flow of electric charge.

Radiant energy refers to energy that moves through vacuum without passing through a material medium.

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.

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

Answer:

it's option D

Answer:

Reacting hydrogen and oxygen gases to make water

Explanation:

Exothermic means that energy is released into the environment, so let's go through the process of elimination.

Allowing meat to thaw after taking it out of the freezer - NO it is endothermic, and takes energy/heat from the environment to thaw.

Popsicle melting on a warm summer day - NO also endothermic, the opposite of exothermic.

Boiling water in a beaker to convert it to steam - NO because we need to add heat, so it doesn't release any energy.

Rolling a ball up a hill - NO, for a ball to roll up a hill, it needs energy from something else, so it's not exothermic.

Reacting hydrogen and oxygen gases to make water - YES this reaction makes new bonds, which releases energy, so this is exothermic.

Among the following choices reacting hydrogen and oxygen gases to make water is an exothermic reaction as it releases energy as new bonds are formed.

An exothermic reaction is defined as a chemical reaction which involves release of energy in the form of light,heat .In these reactions, energy is transferred from system to surroundings rather than taking energy from surroundings into system as in endothermic reactions.

In an exothermic reaction,change in enthalpy is negative.Therefore, it can be inferred that net amount of energy which is required to start the exothermic reaction is less than the net amount which is released by the reaction.

Examples of exothermic reactions are combustion reactions, detonation of nitroglycerin , neutralization reactions and nuclear fission.

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Answer: 89.57 %

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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    

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

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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Answer:

a

Explanation:

A chemical equation is said to balanced only when the number of atoms of each element is the same in both reactants and products side. Rest all options are absurd. Hence, option a is correct.

Balancing of the reaction has no relation with coefficient, molecules or charge of the elements

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.

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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Answer:

The correct option is;

D. Manganese (Mn)

Explanation:

Manganese is very brittle, hard, iron like silvery-gray metal, that is difficult to melt. In air, Manganese slowly disintegrate in a similar manner to iron rusting in water

Manganese and iron have similar chemical and physical properties however manganese is more harder and more brittle than iron

A brittle material is one that easily breaks without deforming elastically

Therefore, manganese, due to its very iron like appearance and brittle nature will be suitable to replace the metal wall and crumble easily when the actor hits it.

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.

Answer:

The freezing point will be -2.046°C.

Explanation:

The freezing point depression equation is [tex]\Delta T_f = k_f \cdot m \cdot i[/tex]

Where;

[tex]\Delta T_f[/tex] = The temperature depression of the freezing point

[tex]k_f[/tex]= The constant of freezing point depression which is solvent dependent = 1.86°C/m

i = The number of particles the substance decomposes into in solution = 1 for sugar (a covalent compound)

m = The molality of the solution = 1.1

Therefore, we have;

[tex]\Delta T_f = 1.86 \times 1.1 \times 1 = 2.046 ^{\circ}C[/tex]

Therefore the freezing point will be 0 - 2.046°C = -2.046°C.