Some Basic Concepts of Chemistry

20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (Atomic weight of Mg =24)

• 75

• 96

• 60

• 60

What is the mass of precipitate formed when 50 mL of 16.9% solution of AgNO₃ is mixed with 50 mL of 5.8% NaCl solution?

(Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)

• 28 g

• 3.5 g 

• 7 g 

• 7 g 

What is the mole fraction of the solute in a 1.00 m aqueous solution? 

• 0.177

• 1.770

• 0.0354

• 0.0354

The number of water molecules is maximum in 

• 18 molecules of water

• 1.8 g of water

• 18 g of water

• 18 g of water

Which has the maximum number of molecules among the following?

• 44 g CO₂

• 48 g O₃

• 8 g H₂

• 8 g H₂

The number of atoms in 0.1 moles of a triatomic gas is (N_A = 6.02 x 10²³ mol^-1)

• 6.026 x 10²²

• 1.806 x 10²³

• 3.600 x 10²³

• 3.600 x 10²³

10 g of hydrogen and 64 of oxygen were filled in a steel vessel and exploded. Amount of water produced in this reaction will be

• 2 mol

• 3 mol

• 4 mol

• 4 mol

Number of moles of MnO₄^- required to oxidies one mole of ferrous oxalate completely in acidic medium will be 

• 0.6 mole

• 0.4 mole

• 7.5 mole

• 7.5 mole

An Organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C, 38.71% and H, 9.67%. The empirical formula of the compound would be

• CH₃O

• CH₂O

• CHO

• CHO

How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl?

• 0.044

• 0.333

• 0.011

• 0.011