Some Basic Concepts of Chemistry

An organic compound crystallises in an ortho rhombic system with two molecules per unit cell. The unit cell dimensions are 12.05, 15.05 and 2.69 Å. If the density of the crystal is 1.419 g cm^-3, then molar mass of compound will be 

• 207 g mol^-1

• 209 g mol^-1

• 308 g mol^-1

• 317 g mol^-1

The molarity of a solution in which 5.3 g Na₂CO₃ is dissolved in 500 mL will be

• 1.0 M

• 0.1 M

• 0.20 M

• 0.2 M

If 5 L of H₂O₂ produces 50 L of O₂ at NTP, H₂O₂ is

• 50 volume

• 10 volume

• 5 volume

• None of the above

If a LPG cylinder contains mixture of butane and isobutane, then the amount of oxygen that would be required for combustion of 1 kg of it will be

• 2.50 × 10³ gm

• 4.50 × 10³ gm

• 180  × 10³ gm

• 3.58 × 10³ gm

8.50g of NH₃ is present in 250ml volume. Its active mass is

• 1.5 ML^-1

• 2.0 ML^-1

• 1.0 ML^-1

• 0.5 ML^-1

Which one of the following is not a unit of energy?

• lit-atm

• Kg m²s^-2

• Nm

• kg ms^-2

Acccording to significant figure convention the result obtained by adding 12.11, 18.0 and 1.012 is

• 31.12

• 31.1

• 31

• 31.122

What is the weight (in gram) of Na₂CO₃ (molar mass = 106) present in 250 mL of its 0.2 M solution? 

• 0.53

• 5.3

• 1.06

• 10.6

An organic compound having C, H and O has 13.13% H, 52.14%C and 34.73 % 0. Its molar mass is 46.068 g. What are its empirical and molecular formulae?

• C₂H₆O, C₄H₁₂O₂

• C₂H₆O, CH₃O

• C₂H₆O, C₂H₆O

• C₂H₆O, C₃H₉O₄

The number of grams/ weight of NH₄Cl required to be added to 3 litres of 0.01 M NH₃ to prepare the buffer of pH = 9.45 at temperature 298 K (K_b for NH₃ is 1.85 × 10^-5)

• 0.354 gm

• 4.55 gm

• 0.455 gm

• 3.55 gm