One mole of CO₂ contains _______.

1

(a)

6.02 x 10²³atoms of C

(b)

3 g of CO₂

(c)

6.02 x 10²³atoms of O

(d)

18.1 x 10²³ molecules of CO₂

5.6 litres of oxygen at NTP is equivalent to _______.

1

(a)

1 mole

(b)

\(\frac { 1 }{ 4 } \)mole

(c)

\(\frac { 1 }{ 8 } \)mole

(d)

\(\frac { 1 }{ 2 } \)mole

Which of the following has the highest mass?

1

(a)

1 g atom of C

(b)

\(\frac { 1 }{ 2 } \)mole of CH₄

(c)

10 mL of water

(d)

3.011 x 10²³atoms of oxygen

The number of significant figures in 0.0101 is _______.

1

(a)

3

(b)

2

(c)

4

(d)

5

The number of grams of oxygen in 0.10 mol of Na₂CO₃· 10H₂O is _______.

1

(a)

20.8 g

(b)

18 g

(c)

108 g

(d)

13 g

Using the unit conversion factor, express 1.54mm s^-1 into pm \(\mu \)s^-1.

1

(a)

1.54 \(\times \)10³pm \(\mu \) s ^-1.

How many moles of atoms are present in 9.0 g of aluminum?

1

(a)

0.33 mol

Calculate the mass of a sample of iron metal that contains 0.250 moles of iron atoms.

1

(a)

14 g

Describe the difference between the mass of mole of oxygen atom (O) and the mass of a mole of oxygen molecule \(({ O) }_{ 2 }\)

1

(a)

A = 14g

Which of these is not an empirical formula?

1

(a)

\({ N }_{ 2 }{ O }_{ 5 }{ ,CCL }_{ 4 },{ C }_{ 6 },{ H }_{ 12 }{ O }_{ 6 },{ C }_{ 2 }{ H }_{ 6 }O.\)

What do you understand by stoichiometric coefficients in a chemical equation?

1

(a)

The coefficients of reactants and products involved in a chemical equation represented by the balanced form are known as stoichiometric coefficients \({ N }_{ 2 }(g){ + }3H_{ 2 }\longrightarrow { 2NH }_{ 3 }(g)\)
The stoichiometric coefficients are 1,2 and 2 respectively.

How many significant figures should be present in the answer of the following calculation? 

1

(a)

Least precise term i.e. 2.5 or 3.5 has two significant figures. Hence, the answer must have two significant figures. 
\(\frac { 2.5\times 1.25\times 3.5 }{ 2.01 } \) = 5.4415\(\approx \) 5.4

If the speed of light is 3.0 × 10⁸ m s^–1, calculate the distance covered by light in 2.00 ns

1

(a)

Time 2.00 ns = 2.00 x 10^-9 s
Distance covered = speed x time
= 3.0 x 10⁸ ms^-1 x 2.00 x 10^-9 s = 0.6 m.

What mass of silver nitrate will react with 5.85 g of sodium chloride to produce 14.35 g of silver chloride and 8.5 g of sodium nitrate, if the law of conservation of mass is true ?

1

(a)

According to law of conservation of law of mass,
mass of reactants = mass of products.
\(\underset{x \mathrm{~g}}{\mathrm{AgNO}_{3}}+\underset{5.85 \mathrm{~g}}{\mathrm{NaCl}} \longrightarrow \underset{14.35 \mathrm{~g}}{\mathrm{AgCl}+\mathrm{NaNO}_{3}}{8.5 \mathrm{~g}}\)
\(\therefore \)  x + 5.85 = 14.35 + 8.5 or  x = 17.0 g

Calculate the number of gram molecules of water in a beaker conatining 576 g of water 

1

(a)

Molecular mass of H₂O = 2\( \times \)1 + 16 = 18 g mol^-1
18g of water = 1 gram of molecule 
\(\therefore\) 576 g of water =\( \frac{1}{18}\)\( \times \)576 = 32 gram molecule

What is the mass in gram of one molecule of caffeine (C₈H₁₀N₄O₂)?

1

(a)

A = 3. \(22\times { 10 }^{ -22 }\) g

Round up the following up to three significant figures:
(i) 34.216
(ii) 10.4107
(iii) 0.04597
(iv) 2808

1

(a)

38.2

3 L water is added to 2 L of 5 M HCl. What is the molarity of HCl in the resultant solution?

1

(a)

2M

Calculate the mass of a molecule of carbon dioxide (CO₂)?

1

(a)

\(7.64\times { 10 }^{ 23 }g\)