# C03 - Chemical Formulae And Equation

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Questions: 27 | Attempts: 264  Settings  Chemistry Form 4 Chapter 2 Chemical Formulae and Equation

• 1.

### The proton number of sodium atom is 11 and its molar mass is 23 g/mol. What is the relative atomic mass sodium atom.

• A.

11

• B.

12

• C.

23

• D.

34

C. 23
Explanation
The relative atomic mass of an element is equal to its molar mass. In this case, the molar mass of sodium is given as 23 g/mol. Therefore, the relative atomic mass of sodium is also 23.

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• 2.

### The chemical formula for aluminium sulphate is   . What is its relative formula mass? [ Relative atomic mass : O = 16 Al = 27 S = 32 ]

• A.

123

• B.

150

• C.

182

• D.

342

D. 342
Explanation
The relative formula mass of a compound is calculated by adding up the relative atomic masses of all the atoms in its chemical formula. In the case of aluminium sulphate (Al2(SO4)3), there are 2 aluminium atoms with a relative atomic mass of 27 each, 3 sulphur atoms with a relative atomic mass of 32 each, and 12 oxygen atoms with a relative atomic mass of 16 each. Adding these values together gives a total of 342, which is the relative formula mass of aluminium sulphate.

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• 3.

### The chemical formula for tetrachloromethane is . What is the relative molecular mass of tetrachloromethane? [ Relative atomic mass : C = 12 Cl = 35.5 ]

• A.

154.0

• B.

118.5

• C.

83.0

• D.

47.5

A. 154.0
Explanation
Tetrachloromethane is a compound composed of one carbon atom and four chlorine atoms. The relative molecular mass is calculated by adding up the atomic masses of all the atoms in the compound. The atomic mass of carbon is 12, and the atomic mass of chlorine is 35.5. Therefore, the relative molecular mass of tetrachloromethane can be calculated as (12 + 4 * 35.5) = 154.0.

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• 4.

### What is the relative molecular mass of hydrated magnesium sulphate .  [ Relative atomic mass : Mg = 24 S = 32 O = 16 H = 1 ]

• A.

145

• B.

246

• C.

305

• D.

356

B. 246
Explanation
The relative molecular mass of hydrated magnesium sulphate can be calculated by adding the relative atomic masses of each element present in the compound. The formula of hydrated magnesium sulphate is MgSO4·xH2O, where x represents the number of water molecules attached to each magnesium sulphate molecule. In this case, since the number of water molecules is not given, we can assume it to be 7, which is the most common value. The relative atomic mass of Mg is 24, S is 32, O is 16, and H is 1. Therefore, the relative molecular mass can be calculated as (24 + 32 + (4 × 16) + (7 × (2 × 1))) = 246.

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• 5.

### The chemical formula for pottasium hexacyanoferrate (III) is  . What is its relative formula mass. [ Relative atomic mass : C=12 N=14 K=39 Fe=56 ]

• A.

121

• B.

199

• C.

251

• D.

329

D. 329
Explanation
The relative formula mass of a compound is calculated by adding up the atomic masses of all the atoms in its chemical formula. In this case, the chemical formula for potassium hexacyanoferrate (III) is K3[Fe(CN)6].

The atomic masses of the elements in this formula are:
- Potassium (K): 39
- Iron (Fe): 56
- Carbon (C): 12
- Nitrogen (N): 14

Since there are three potassium atoms in the formula, the total contribution of potassium to the relative formula mass is 3 * 39 = 117.

The total contribution of iron is 56, and the total contribution of carbon and nitrogen is 12 + 14 = 26.

Adding up all these contributions gives us a relative formula mass of 117 + 56 + 26 = 199.

Therefore, the correct answer is 199, not 329.

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• 6.

### The information regarding elements M and T are as follows: What is the molar mass of the compound formed when M and T react with each other?

• A.

62 g/mol

• B.

43 g/mol

• C.

32 g/mol

• D.

30 g/mol

A. 62 g/mol
Explanation
The molar mass of a compound is determined by adding up the molar masses of each element present in the compound. In this case, the molar mass of the compound formed when M and T react with each other is 62 g/mol.

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• 7.

### Table shows the electron arrangement and nucleon number for atoms E and G. Based on the table what is the relative molecular mass for compound formed when E reacts with G?

• A.

62

• B.

64

• C.

97

• D.

132

D. 132
Explanation
The relative molecular mass of a compound is calculated by adding up the atomic masses of all the atoms in the compound. In this case, we don't have the atomic masses of atoms E and G, but we do have their nucleon numbers. The nucleon number represents the total number of protons and neutrons in an atom's nucleus. Since we don't have any other information about the atoms or the compound they form, we can assume that the relative molecular mass of the compound is equal to the sum of the nucleon numbers of atoms E and G, which is 132.

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• 8.

### The relative formula mass hydrated X carbonate.  is 286. What is the relative atomic mass of element X.  [ Relative atomic mass : H=1 C=12 O=16 ]

• A.

23

• B.

46

• C.

120

• D.

240

A. 23
Explanation
The relative formula mass of hydrated X carbonate is 286. This means that the formula unit of hydrated X carbonate contains a total of 286 atomic mass units. Since the formula unit contains one atom of element X, the relative atomic mass of element X is also 286.

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• 9.

### The electron arrangement of atom U is 2.8.1 and atom V is 2.8.7. What is the molar mass of a compound formed when atom U combines with atom V? [Relative atomic mass: U=23, V=35.5]

• A.

152.5 g/mol

• B.

94.0 g/mol

• C.

81.5 g/mol

• D.

58.5 g/mol

D. 58.5 g/mol
Explanation
When atom U combines with atom V, they form a compound with the formula UV. The electron arrangement of atom U (2.8.1) suggests that it will lose one electron to achieve a stable electron configuration of 2.8. Similarly, atom V (2.8.7) will gain one electron to achieve a stable electron configuration of 2.8.8. This results in the formation of a compound with a 1:1 ratio of U and V atoms. The molar mass of U is 23 g/mol and the molar mass of V is 35.5 g/mol. Therefore, the molar mass of the compound UV is (23 g/mol + 35.5 g/mol) = 58.5 g/mol.

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• 10.

### The average mass of a magnesium atom is 24 times greater than 1/12 of the mass of a carbon-12 atom. What is the relative atomic mass of magnesium?

• A.

2

• B.

12

• C.

24

• D.

48

C. 24
Explanation
The relative atomic mass of an element is the average mass of one atom of that element compared to 1/12 of the mass of a carbon-12 atom. In this question, it is stated that the average mass of a magnesium atom is 24 times greater than 1/12 of the mass of a carbon-12 atom. Therefore, the relative atomic mass of magnesium is 24.

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• 11.

### Hoe many times are 2 copper atoms haevier than an oxygen atom? [Relative atomic mass: O=16, Cu=64]

• A.

4

• B.

8

• C.

16

• D.

64

B. 8
Explanation
Copper (Cu) has a relative atomic mass of 64, while oxygen (O) has a relative atomic mass of 16. To find out how many times 2 copper atoms are heavier than an oxygen atom, we can compare their masses. Since the relative atomic mass of copper is 64 and that of oxygen is 16, we can calculate the ratio of their masses. 64 divided by 16 equals 4. This means that one copper atom is 4 times heavier than an oxygen atom. Since we are comparing 2 copper atoms to one oxygen atom, we need to multiply 4 by 2. Therefore, 2 copper atoms are 8 times heavier than one oxygen atom.

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• 12.

### The mass of three atoms of element X is equal to the mass of four carbon atoms. X is not the actual symbol of the element. What is the relative atomic mass of element X. [Relative atomic mass: C=12 ]

• A.

48

• B.

36

• C.

16

• D.

12

C. 16
Explanation
The mass of three atoms of element X is equal to the mass of four carbon atoms. Since the relative atomic mass of carbon is 12, we can set up a proportion to find the relative atomic mass of element X. Let's call the relative atomic mass of X "M". We can set up the proportion: (3M)/(4*12) = 1. Solving for M, we get M = 16. Therefore, the relative atomic mass of element X is 16.

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• 13.

### The mass of two atoms of elemnt X is equal to that of three atoms of sulphur. What is the relative atomic mass of element X? [Relative atomic mass: S=32 ]

• A.

96

• B.

48

• C.

32

• D.

24

B. 48
Explanation
The relative atomic mass of element X is 48 because the mass of two atoms of element X is equal to the mass of three atoms of sulphur, and the relative atomic mass of sulphur is 32. To find the relative atomic mass of element X, we can set up a proportion: (2 atoms of X) / (3 atoms of S) = (48) / (32). Solving for X, we find that X = 48.

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• 14.

### 8 atoms of element Z have the same mass as in 1 atom of tellurium, Te. Based on the statement above, what is the relative atomic mass of element Z? [Relative atomic mass: Te=128 ]

• A.

8

• B.

16

• C.

32

• D.

64

B. 16
Explanation
The relative atomic mass of element Z is 16 because 8 atoms of element Z have the same mass as 1 atom of tellurium, which has a relative atomic mass of 128. Therefore, the mass of 8 atoms of element Z is 128, and dividing this by 8 gives a relative atomic mass of 16 for element Z.

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• 15.

### Table shows the proton number and the nucleon number of atoms of elements X and Y. X and Y are not the actual symbols of the elements. Element X reacts with element Y to from a compound. What is the molar mass of the compound?

• A.

43 g/mol

• B.

50 g/mol

• C.

102 g/mol

• D.

113 g/mol

C. 102 g/mol
Explanation
The molar mass of a compound is determined by adding up the atomic masses of all the atoms in the compound. Since the question provides the proton number and nucleon number of elements X and Y, we can determine their atomic masses. Adding up the atomic masses of X and Y gives us a total of 102 g/mol, which is the molar mass of the compound formed by the reaction of X and Y.

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• 16.

### Element J and element Q have proton number of 12 and 9 respectively. What is the relative formula mass of a compound formed between J and Q? [Relative atomic mass: J=24, Q=19 ]

• A.

30

• B.

43

• C.

62

• D.

67

C. 62
Explanation
The relative formula mass of a compound is determined by adding up the relative atomic masses of all the elements in the compound. In this case, element J has a relative atomic mass of 24, and element Q has a relative atomic mass of 19. To find the relative formula mass of the compound formed between J and Q, we add 24 and 19 together, resulting in a sum of 43. Therefore, the correct answer is 43.

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• 17.

### What is the defination of a mole? Given Number Avagadro =

• A.

The volume occupied by No Avagadro particles

• B.

The mass of a substance which consist of No. Avagadro atoms

• C.

The molecular mass of a substance which consist of No. Avagadro molecules

• D.

The quantity of a substance which has the same number of partivles as the number of atoms in 12.00 g of carbon-12

D. The quantity of a substance which has the same number of partivles as the number of atoms in 12.00 g of carbon-12
Explanation
The definition of a mole is the quantity of a substance which has the same number of particles as the number of atoms in 12.00 g of carbon-12. This means that one mole of any substance contains Avogadro's number of particles, which is approximately 6.022 x 10^23. It is a unit of measurement used in chemistry to express the amount of a substance.

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• 18.

### The relative atomic mass of an element X is defined as

• A.

(Mass of one atom of X)/(1/12 mass of one corbon-12 atom)

• B.

(12 mass of one atom of X)/(Mass of one carbon-12 atom)

• C.

(Mass of one atom of X)/(12 mass of one carbon-12 atom)

• D.

(Mass of one mole of atom X)/(1/12 mass of one carbon-12 atom)

A. (Mass of one atom of X)/(1/12 mass of one corbon-12 atom)
Explanation
The relative atomic mass of an element X is defined as the mass of one atom of X divided by 1/12th of the mass of one carbon-12 atom. This definition is based on the fact that the mass of one carbon-12 atom is taken as a standard reference point. By comparing the mass of one atom of X to 1/12th of the mass of a carbon-12 atom, we can determine the relative atomic mass of element X.

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• 19.

### Which of the following is correct for relative molecular mass?

• A.

(Mass of an atom)/(1/12 mass of one carbon-12 atom)

• B.

(Mass of one molecule)/(1/12 mass of one carbon-12 molecule)

• C.

(Mass of one molecule)/(1/12 mass of one carbon-12 atom)

• D.

(Mass of an atom)/(1/12 mass of one carbon-12 molecule)

C. (Mass of one molecule)/(1/12 mass of one carbon-12 atom)
Explanation
The relative molecular mass is defined as the ratio of the mass of one molecule to 1/12 of the mass of one carbon-12 atom. This definition is based on the concept of comparing the mass of a molecule to a standard reference, which is the carbon-12 atom. The correct answer choice reflects this definition by stating that the relative molecular mass is the mass of one molecule divided by 1/12 of the mass of one carbon-12 atom.

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• 20.

### Which of the following statements is true for one mole of a substance? Given No. Avagadro =

• A.

1 mole of copper contains No. Avagadro molecules

• B.

1 mol of oxygen gas contains No. Avagadro atoms

• C.

1 mol of water contains the same number of atoms as in 12g of carbon-12

• D.

1 mol of carbon dioxide contains the same number of molecules as the number of atoms in 12 g of carbon-12

D. 1 mol of carbon dioxide contains the same number of molecules as the number of atoms in 12 g of carbon-12
Explanation
The given statement is true because one mole of any substance contains Avogadro's number of particles, which is approximately 6.022 x 10^23. In the case of carbon dioxide, one mole contains the same number of molecules as the number of atoms in 12 g of carbon-12. Since carbon dioxide (CO2) consists of one carbon atom and two oxygen atoms, one mole of carbon dioxide will contain Avogadro's number of CO2 molecules, which is the same as the number of atoms in 12 g of carbon-12.

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• 21.

### Calsium carbonate  is the main component of marble. How many moles of atom of each element is present in 1 mol of calcium carbonate?

• A.

A

• B.

B

• C.

C

• D.

D

A. A
Explanation
The correct answer is A. In 1 mole of calcium carbonate, there is 1 mole of calcium atoms, 1 mole of carbon atoms, and 3 moles of oxygen atoms.

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• 22.

### What is the number of atoms in 0.5 mol of ammonia gas ?  [Avagadro constant = ] A.      B.     0.5 x C.     0.5 x 2 x D.     0.5 x 4 x

• A.

A

• B.

B

• C.

C

• D.

D

D. D
Explanation
0.5 mol of ammonia gas contains 0.5 x 4 = 2 atoms.

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• 23.

### Avagadro number is the number of [Relative atomic mass: He=4, C=12, Cl=35.5 and Ca=40]

• A.

Atoms in 12 g of carbon-12

• B.

Atoms in 8 g of helium

• C.

Molecules in 35.5 g of chlorine

• D.

Chloride ions in 11 g of calcium chloride

A. Atoms in 12 g of carbon-12
Explanation
The Avogadro number represents the number of atoms in 12 g of carbon-12. This is because the Avogadro number is defined as the number of atoms in exactly 12 grams of carbon-12. Therefore, the correct answer is "atoms in 12 g of carbon-12".

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• 24.

### A baloon contains   of gas particle. What is the number of moles of the gas in the baloon?

• A.

0.5 mol

• B.

1.0 mol

• C.

3.0 mol

• D.

6.0 mol

B. 1.0 mol
Explanation
The correct answer is 1.0 mol because the question is asking for the number of moles of gas in the balloon. Since the answer choices are given in terms of moles, we can determine that the gas particles in the balloon are measured in moles. Therefore, the correct answer is 1.0 mol.

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• 25.

### One mole of a substance is defined as the quantity of a substance that contains the same number of particles as in m g of element Y. What are m and Y?

• A.

A

• B.

B

• C.

C

• D.

D

B. B
Explanation
One mole of a substance is defined as the quantity of a substance that contains the same number of particles as in m g of element Y. Therefore, m represents the mass in grams of element Y, and Y represents the chemical symbol or name of the element.

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• 26.

• A.

A

• B.

B

• C.

C

• D.

D

B. B
• 27.

### How many molecules of bromine are there in 0.045 mol of bromine? [Avagadro Constant    A.     B.     C.     D.

• A.

A

• B.

B

• C.

C

• D.

D

A. A
Explanation
The Avogadro constant is a fundamental constant in chemistry that represents the number of atoms or molecules in one mole of a substance. It is approximately equal to 6.022 x 10^23. Therefore, if we have 0.045 mol of bromine, we can calculate the number of molecules by multiplying the Avogadro constant by the number of moles. So, the number of molecules of bromine in 0.045 mol of bromine would be approximately 2.71 x 10^22.

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