NEET Some Basic Concepts Of Chemistry — Set 13

Question 1

A mixture of 10 g $ \ce{CO} $ and 16 g $ \ce{O2} $ is ignited to form $ \ce{CO2} $. What is the mass of $ \ce{CO2} $ produced? (Atomic masses: C = 12, O = 16)

Accepted Answer

Reaction: $ \ce{2CO + O2 -> 2CO2} $. Moles: $ \ce{CO} $ = $ \frac{10}{28} $ ≈ 0.357 mol, $ \ce{O2} $ = $ \frac{16}{32} $ = 0.5 mol. 2 mol $ \ce{CO} $ need 1 mol $ \ce{O2} $; 0.357 mol need 0.1785 mol $ \ce{O2} $ (available). 0.357 mol $ \ce{CO} $ produces 0.357 mol $ \ce{CO2} $ = 0.357 × 44 ≈ 15.71 g.

Question 2

A gas occupies 4.48 L at STP and weighs 2 g. What is its molar mass?

Accepted Answer

Moles = $ \frac{4.48}{22.4} $ = 0.2 mol. Molar mass = $ \frac{2}{0.2} $ = 10 g/mol.

Question 3

A solution of $ \ce{KOH} $ has a density of 1.1 g/mL and a molarity of 2 M. What is its molality? (Molar mass: $ \ce{KOH} $ = 56 g/mol)

Accepted Answer

Mass of 1 L solution = 1000 × 1.1 = 1100 g. Mass of $ \ce{KOH} $ = 2 × 56 = 112 g. Mass of water = 1100 - 112 = 988 g = 0.988 kg. Molality = $ \frac{2}{0.988} $ ≈ 2.02 m.

NEET Chemistry: Some Basic Concepts Of Chemistry — Practice Set 13

Q1. A mixture of 10 g \( \ce{CO} \) and 16 g \( \ce{O2} \) is ignited to form \( \ce{CO2} \). What is the mass of \( \ce{CO2} \) produced? (Atomic masses: C = 12, O = 16)

Q2. A gas occupies 4.48 L at STP and weighs 2 g. What is its molar mass?

Q3. A solution of \( \ce{KOH} \) has a density of 1.1 g/mL and a molarity of 2 M. What is its molality? (Molar mass: \( \ce{KOH} \) = 56 g/mol)

Q4. What mass of \( \ce{Fe} \) can be obtained from 16 g of \( \ce{Fe2O3} \) using excess \( \ce{CO} \)? (Molar masses: \( \ce{Fe2O3} \) = 160 g/mol, Fe = 56 g/mol)

Q5. A solution contains 25 ppm of \( \ce{NaNO3} \) by mass in water. What is its molarity if the density is 1 g/mL? (Molar mass: \( \ce{NaNO3} \) = 85 g/mol)

Q6. What is the mass percentage of \( \ce{NH3} \) in a solution made by dissolving 3.4 g of \( \ce{NH3} \) in 16.6 g of water? (Molar mass: \( \ce{NH3} \) = 17 g/mol)

Q7. A mixture of 8 g \( \ce{CH4} \) and 32 g \( \ce{O2} \) is ignited to form \( \ce{CO2} \) and \( \ce{H2O} \). What is the mass of \( \ce{CO2} \) produced? (Atomic masses: C = 12, H = 1, O = 16)

Q8. A 0.1 M \( \ce{NaOH} \) solution is prepared using 4 g of \( \ce{NaOH} \). What is the volume of the solution in liters? (Molar mass: \( \ce{NaOH} \) = 40 g/mol)

Q9. How many grams of \( \ce{Zn} \) are required to produce 4.48 L of \( \ce{H2} \) at STP with excess \( \ce{HCl} \)? (Atomic mass: Zn = 65)

Q10. How many grams of \( \ce{ZnSO4} \) are required to produce 6.5 g of \( \ce{Zn} \) with excess \( \ce{H2SO4} \)? (Molar masses: \( \ce{ZnSO4} \) = 161.5 g/mol, Zn = 65 g/mol)