class 11 some basic concepts

The empirical formula and molecular mass of a compound are CH20 and 180g respectively. What will be the molecular formula of the compound?

• (a) C₉H₁₈0₉,

• (b) CH₂0

• (c) C₆H₁₂0₆

• (d) C₂H₄0₂

What is the mass per cent of carbon in carbon dioxide

• (a) 0.034%

• (b) 27.27%

• (c) 3.4%

• (d) 28.7%

. Which of the following reactions is not correct according to the law of conservation of mass?

• (a) 2Mg(s) + 0₂(g) →2MgO(s)

• (b) C₃H₈(g) + 0₂(g) →C0₂(g) + H₂O(g)

• (c) P₄(s) + 50₂(g) →P₄O₁₀(s)

• (d) CH₄(g) + 20₂(g) → C0₂(g) + 2H₂0(g

One mole of oxygen gas at STP is equal to____ .

• (a) 6. 022 x 1023 molecules of oxygen

• (b) 6.022 x 1023 atoms of oxygen

• (c) 16 g of oxygen .

• (d) 32 g of oxygen.

16 g of oxygen has the same number of molecules as in

• (a) 16 g of CO

• (b) 28 g of N2

• (c) 14g of N2

• (d) 1.0 gof H2,