Answer:
1) The percentage of oxygen in dry air is _______
C. 21
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
B. CARBON DIOXIDE
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Answer: The percentage of oxygen in dry air is . 21
Explanation: Ammonia gases was present in large amounts in the easth7s earliest atmosphere
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(b)
Huiting wanted to find out the hardness of two materials H and F. She used a
rounded object made of material G and forced it into each material with the
same force. The results of her experiment are shown below.
rounded object of
material G
rounded object
of material G
3 mm
1 mm
object of
material H
object of
material F
List materials F, G, H in increasing order of hardness. Explain your answer.
[2]
Object named H is harder than Object F due to its thickness.
The object of material H is harder than the object of material F due to the difference in thickness. The thickness of Material Object H is 3 millimeters compared to Material Object F which is 1 millimeter thick, so applying the same amount of force on both objects, Material Object H does not show any change in its structure while on the other hand, the shape of the object F changes due to a lower hardness.
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Which of the following units are commonly used in chemistry? A Kelvin b ampere c fluid ounce d kilogram
Explanation:
your answer is Kelvin because it is the SI unit of temperature
A small gap in skit in railway track why
Answer:
To reduce the bending of the railway
Explanation:
During summer(heat) metals tend to expand in size. The skits/gaps are present in the railway so that the metal could expand without causing bending of the railway track.
why hydrogen and oxygen all around us dows not form water
Answer:together doesn't make water
Explanation:
together doesn't make water
Determine the type of alcohol corresponding to each given description or name. 3-ethyl-3-pentanol Choose... An alcohol with two other carbons attached to the carbon with the hydroxyl group Choose... An alcohol with three other carbons attached to the carbon with the hydroxyl group Choose... 1-pentanol Choose... 2-hexanol Choose... An alcohol with one other carbon attached to the carbon with the hydroxyl group Choose...
Answer:
An alcohol with three other carbons attached to the carbon with the hydroxyl group
An alcohol with two other carbons attached to the carbon with the hydroxyl group
Explanation:
If we look at 3-ethyl-3-pentanol, we will discover that the compound is a tertiary alcohol. That is, the carbon atom bearing the hydroxyl group is attached to three other carbon atoms as gown in image 1 attached.
For 2-hexanol, the carbon atom bearing the hydroxyl group is attached to two other carbon atoms hence the alcohol is a secondary alcohol. The compound is shown in image 2 attached.
What does the reducing agent do in a redox reaction? (A.P.E.X)
Answer:
The reducing agent donates electron to the oxidizing agent and gets oxidized itself
Explanation:
In an oxidation-reduction reaction, also known as REDOX reaction, one of the reactants is called OXIDIZING AGENT while the other is called REDUCING AGENT. The reducing agent is called so because it reduces another substance in the reaction.
It reduces another atom/ion by donating electrons to that atom, hence, getting oxidized itself in the process. For example, in the following reaction:
H2 + F2 → 2HF
Fluorine is getting oxidized from -2 to 0 by donating electrons to H and reducing it from +2 to 0.
Answer:
Reduces another atom
Explanation:
:)
Which option explains why this amino acid can act
both an acid and a base?
(1 point)
It contains both an amino functional group and a carboxyl functional group. In a solution, the amino group can
increase acidity, while the carboxyl group can decrease acidity
It contains both an amino functional group and a methyl functional group. In a solution, the amino group can
increase acidity, while the methyl group can decrease acidity
It contains both an amino functional group and a carboxyl functional group. In a solution, the amino group can
decrease acidity, while the carboxyl group can increase acidity
It contains both an amino functional group and a methyl functional group. In a solution, the amino group can
decrease acidity, while the methyl group can increase acidity
The correct answer is: It contains both an amino functional group and a carboxyl functional group. In a solution, the amino group can
decrease acidity, while the carboxyl group can increase acidity.
The carboxyl functional group is acidic while the amine group is basic.
In an amino acid, there are two functional groups;
The amine groupThe carboxyl groupThe carboxyl functional group is acidic because it contains a replaceable or ionizable hydrogen ion. The amine group on the other hand is capable of accepting a proton hence it is basic.
Therefore, In a solution, the amine group can decrease acidity, while the carboxyl group can increase acidity.
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6. What type of bond is called covalent bond?
Answer:
ECovalent bond, in chemistry, the interatomic linkage that results from the sharing of an electron pair between two atoms. The binding arises from the electrostatic attraction of their nuclei for the same electrons. ... Silicon, carbon, germanium, and a few other elements form covalently bonded solids.
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As the mass of the nucleus increases, what happens to the ratio of neutrons to protons in stable isotopes? A. The neutron:proton ratio decreases. B. The neutron:proton ratio increases. C. The neutron:proton ratio remains 1:1. D. The neutron:proton ratio remains 1.5:1.
PLZ HELP ME WITH MY WORK
Answer:
neutrons should be added with the protons
Differentiate between emperical and
molecular formula. Give an example of
a substance having different emperical
and molecular formula
Answer:
Here’s an example:
CH (methylene) is the empirical formula.
C2H2 is a molecular formula. It is a gas called Ethyne.
C8H8 is an oily liquid called Styrene. It is also a molecular formula.
Now compare: even though the empirical formula for these compounds is the same, they have different molecular formulas and different properties.
Explanation:
Some background information:
The empirical formula is the formula with the lowest whole number ratio of an element in a compound. A molecular formula is the chemical formula of a (molecular) compound. The molecular formula gives us the exact number of atoms or moles in that compound.
I have attached pictures for a better understanding of the empirical formula.
What is the atomic number of the atom in the diagram above please ?
Answer:
5
Explanation:
The atomic number is the number of protons in an atom. Protons are the positively charged particles in the nucleus. The number of protons define the identity of an element. An element with 5 protons is Boron, no matter how many neutrons may be present.
The atomic number of the atom shown in the diagram is 5.
What is the atomic number?The atomic number of an element refers to the number of protons in the nucleus of its atoms. It uniquely identifies an element and determines its chemical properties.
In the diagram, there are 5 proton numbers in the nucleus of the atom. In other words, this means that the atomic number of the atom is 5.
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Do cycloalkanes easily take part in addition reactions?
Answer:
The reactions of the cycloalkanes are generally just the same as the alkanes, with the exception of the very small ones - particularly cyclopropane. ... In the absence of UV light, cyclopropane can undergo addition reactions in which the ring is broken
would Nitrogen Dioxide be ionic or covalent
Explanation:
The nitrogen dioxide is a covalent compound where one nitrogen is the central atom which is bonded to two oxygen atoms, where one oxygen atom is bonded by a single bond and other oxygen atom by a double bond.
Answer: colavent
Explanation:
How would you upscale your chemistry learning through
the knowledge of periodic table. Explain? (5 marks worth answer)
Explanation:
The periodic table brings order to information about the chemical elements. It helps chemists to understand why elements react as they do. Elements in the same group have similar chemical properties. This is because they have the same number of outer electrons and the same valency
For the reaction 2HNO3 + Mg(OH)2 + Mg(NO3)2 + 2H20, how many
grams of magnesium nitrate are produced from 3.54 mol of nitric
acid, HNO3?
O a. 220
O b. 263
O c. 1050
O d. 175
Answer:
B
Explanation:
A 240g hydrated sodium sulphide contains 162g of water of crystallisation. What is the correct molecular formula for this compound?
What is the answer and working
Answer:
Explanation:
First of all, 1 mol of Sodium Sulphide has molecular mass of
S = 32
Na2 = 2*23 = 46
The formula of NaS is actually Na2S. It's molecular mass = 78
How many grams of Na2S are present
Grams present = 240 - 162 = 78 which is exactly 1 mol.
The remainder is water.
The molecular mass of water = 2 + 16 = 18
162 grams of water = 162/18 = 9 mols of water.
So the correct formula is Na2S*9H20
Question 3: Functional Groups
Identify the type of molecule from the name of the molecule.
Answer:
1. Organic Alcohol
2. Ester (specifically acetate ester)
3. Organic Alcohol
4. Carboxylic acid
5. Ketone
6. Ether
7. Amine
Explanation:
You can tell what type it is both from the nomenclature and looking at the functional group on the molecular structure. Hope this helps!
Which atom is abundant in the universe
Answer:
hydrogen is abundant in nature
A hot metal plate at 150°C has been placed in air at room temperature. Which event would most likely take place over the next few minutes?
- Molecules in both the metal and the surrounding air will start moving at lower speeds.
-Molecules in both the metal and the surrounding air will start moving at higher speeds.
-The air molecules that are surrounding the metal will slow down, and the molecules in the metal will speed up.
-The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
Answer:
it will dilute to its natrual state. so c
Explanation:
19. If 23.4 grams of hydrogen gas were produced by the reaction below, how many grams of aluminum chloride were produced? (2 points) 2 Al + 6 HCl yields 2 AlCl3 + 3 H2 516 g AlCl3 774 g AlCl3 1030 g AlCl3 1550 g AlCl3
Answer:
1040
Explanation:
you can use the mole to mole ratios of aluminum chloride and hydrogen gas,you first have to find the number of moles of hydrogen gas..the number of moles of hydrogen gas are 11.7(23.4/2)
2AlCl3+3H2
2 : 3
x :11.7
3x/3=23.4/3
x=7.8g/mol
then find the number of grams of aluminum chloride
m=n×mr
=7.8×133.341
=1040g
I hope this helps and sorry if it's wrong
Which of the following would increase the pressure of a gas in a container?
A. Decreasing the kinetic energy of the gas
B. Increasing the temperature of the gas
C. Decreasing the number of gas particles
D. Increasing the volume of the container
The only option that would increase the pressure of a gas in a container is B. Increasing the temperature of the gas. Option B
To understand which factor would increase the pressure of a gas in a container, we need to consider the relationship between pressure and various variables in the ideal gas law and the kinetic theory of gases.
The ideal gas law states that pressure (P) is directly proportional to the number of gas particles (n), the temperature (T), and inversely proportional to the volume (V) of the container. Mathematically, it can be expressed as:
PV = nRT
where R is the ideal gas constant.
Based on this equation, we can analyze the options given:
A. Decreasing the kinetic energy of the gas: According to the ideal gas law, temperature is directly proportional to pressure. Therefore, decreasing the kinetic energy (which is related to temperature) would decrease the pressure, not increase it.
B. Increasing the temperature of the gas: As mentioned above, temperature is directly proportional to pressure. Increasing the temperature of the gas would increase its kinetic energy, resulting in more frequent and energetic collisions with the container walls, thus increasing the pressure.
C. Decreasing the number of gas particles: According to the ideal gas law, the number of gas particles (n) is directly proportional to pressure. Therefore, decreasing the number of gas particles would decrease the pressure, not increase it.
D. Increasing the volume of the container: According to the ideal gas law, volume (V) is inversely proportional to pressure. Increasing the volume of the container would decrease the pressure, not increase it.
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Out of a box of 46 matches, 22 lit on the first strike. What percentage of the matches in the box did not light on the first strike?
Answer: 52.17%
Explanation:
Number of matches in the box = 46
Number of matches that lit on the first strike = 22
Number of matches that did not light on the first strike = 46 - 22 = 24
Therefore, the percentage of the matches in the box did not light on the first strike will be:
= (Number of matches that did not light on the first strike / Number of matches in the box) × 100
= 24/46 × 100
= 52.17%
Therefore, the percentage of the matches in the box that did not light on the first strike is 52.17%.
What is the density of ammonia (NH3) at 273 K and 1.00 atm?
A - 0.7601 g/L
B - 0.982 g/L
C - 1.23 g/L
D - 2.43 g/L
Answer:
0.7602 g/L
Explanation:
We'll begin by calculating the molar mass of NH₃. This can be obtained as follow:
Molar mass of NH₃ = 14.01 + (3×1.01)
= 14.01 + 3.03
= 17.04 g/mol
Finally, we shall determine the density of ammonia, NH₃. This can be obtained as follow:
Temperature (T) = 273 K
Pressure (P) = 1 atm
Molar mass of NH₃ (M) = 17.04 g/mol
Gas constant (R) = 0.0821 atm.L/Kmol
Density (D) =?
D = PM / RT
D = (1 × 17.04) / (0.0821 × 273)
D = 17.04 / 22.4133
D = 0.7602 g/L
Answer:
It is A
Explanation:
A piece of unknown metal with mass 68.6 g is heated to an initial temperature of 100 °C and dropped into 8.4 g of water (with an initial temperature of 20 °C) in a calorimeter. The final temperature of the system is 52.1°C. The specific heat of water is 4.184 J/g*⁰C. What is the specific heat of the metal?
0.171
0.343
1.717
3.433
Answer:
1.717
Explanation:
PLZ HELP ME WITH MY WORK
Answer:High density
Explanation:
The metal doesn't remains gas at room tempreture, it doesn't have brittleness property and it is not poor conductor of electricity .But, it has high density .
Hope, it would be correct.
balance the equation:2Na+3H2O-2NaOH+H2
Answer:
2Na + 2H2O → 2NaOH + H2
Explanation:
A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products.
What amount of SeC16 is needed to produce 4.45 mol of chlorine gas in the
reaction Seclo +0 218) —SeO, +3Cl2te)?
2.85 mol
0.95 mol
5.70 mol
8.55 mol
1.49 mol
Answer:
1.48 moles of SeCl6 are needed
Explanation:
Based on the reaction:
SeCl6 + O2 → SeO2 + 3Cl2
1 mole of SeCl6 reacts producing 3 moles of Cl2.
To solve this question we need to use the conversion factor:
1mol SeCl6 = 3mol Cl2
As we want to produce 4.45 moles of Cl2, we need:
4.45 mol Cl2 * (1mol SeCl6 / 3mol Cl2) =
1.48 moles of SeCl6 are neededwhat is bonding in chemistry
Explanation:
A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds.
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Answer:
Check Down
Explanation:
A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bond.
The number of particles in 8 g 02 molecules are
Answer:
cholesterol
Explanation:
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