NEET Some Basic Concepts Of Chemistry — Set 9

Question 1

What volume of $ \ce{O2} $ at STP is needed to burn 36 g of carbon to $ \ce{CO2} $, assuming 25% wastage? (Atomic mass: C = 12)

Accepted Answer

Reaction: $ \ce{C + O2 -> CO2} $. Moles of C = $ \frac{36}{12} $ = 3 mol; requires 3 mol $ \ce{O2} $. Volume at STP = 3 × 22.4 = 67.2 L. With 25% wastage, total = $ \frac{67.2}{0.75} $ ≈ 89.6 L.

Question 2

What is the mole fraction of water in a solution containing 36 g of water and 46 g of ethanol ($ \ce{C2H5OH} $)? (Molar masses: $ \ce{H2O} $ = 18 g/mol, ethanol = 46 g/mol)

Accepted Answer

Moles of $ \ce{H2O} $ = $ \frac{36}{18} $ = 2 mol; moles of ethanol = $ \frac{46}{46} $ = 1 mol. Total moles = 2 + 1 = 3. Mole fraction of water = $ \frac{2}{3} $ ≈ 0.667.

Question 3

What is the mole fraction of ethanol in a solution where 46 g of ethanol ($ \ce{C2H5OH} $) is mixed with 18 g of water? (Molar masses: ethanol = 46 g/mol, water = 18 g/mol)

Accepted Answer

Moles of ethanol = $ \frac{46}{46} $ = 1 mol. Moles of water = $ \frac{18}{18} $ = 1 mol. Total moles = 1 + 1 = 2; mole fraction = $ \frac{1}{2} $ = 0.5.

NEET Chemistry: Some Basic Concepts Of Chemistry — Practice Set 9

Q1. What volume of \( \ce{O2} \) at STP is needed to burn 36 g of carbon to \( \ce{CO2} \), assuming 25% wastage? (Atomic mass: C = 12)

Q2. What is the mole fraction of water in a solution containing 36 g of water and 46 g of ethanol (\( \ce{C2H5OH} \))? (Molar masses: \( \ce{H2O} \) = 18 g/mol, ethanol = 46 g/mol)

Q3. What is the mole fraction of ethanol in a solution where 46 g of ethanol (\( \ce{C2H5OH} \)) is mixed with 18 g of water? (Molar masses: ethanol = 46 g/mol, water = 18 g/mol)

Q4. A solution of \( \ce{NaOH} \) has a molarity of 1 M and a density of 1.04 g/mL. What is its molality? (Molar mass: \( \ce{NaOH} \) = 40 g/mol)

Q5. How many grams of \( \ce{SO2} \) are produced when 8 g of sulfur is burned in 12 g of \( \ce{O2} \)? (Atomic masses: S = 32, O = 16)

Q6. A 1 L sample of a gas at STP weighs 1.25 g and contains only carbon and hydrogen. If it produces 1.76 g of \( \ce{CO2} \) on burning, what is its molecular formula? (Atomic masses: C = 12, H = 1)

Q7. What is the mass of \( \ce{BaSO4} \) produced when 23.3 g of \( \ce{BaCl2} \) reacts with excess \( \ce{Na2SO4} \)? (Molar masses: \( \ce{BaCl2} \) = 208 g/mol, \( \ce{BaSO4} \) = 233 g/mol)

Q8. How many grams of \( \ce{Fe} \) are required to produce 8.96 L of \( \ce{H2} \) at STP with excess \( \ce{HCl} \)? (Atomic mass: Fe = 56)

Q9. A solution contains 15 ppm of \( \ce{CHCl3} \) by mass in water. What is its molality? (Molar mass: \( \ce{CHCl3} \) = 119.5 g/mol)

Q10. What is the mass of \( \ce{AgCl} \) produced when 34 g of \( \ce{AgNO3} \) reacts with excess \( \ce{NaCl} \)? (Molar masses: \( \ce{AgNO3} \) = 170 g/mol, \( \ce{AgCl} \) = 143.5 g/mol)