STANDARD 11 CHEMISTRY 01: SOME BASIC CONCEPTS OF CHEMISTRY PART 2

Which of the following statements is INCORRECT?

Atoms may or may not have free existence.
A molecule may contain atoms of same elements or different elements.
A molecule can be divided into the its constituent atoms by simple methods.
The properties of constituent atoms and the compounds formed from them are completely different.

The number of sulphur atoms present in 0.2 moles of S8 molecules is _______.

9.63 x 10²³
9.63 x 10²³
1.20 x 10²³
4.82 x 10²³

Which of the following indicates CORRECT reaction for photosynthesis?

C + O2 + H2O + sunlight → Products
CO + H2O + sunlight → Products
CO2 + H2O + sunlight → Products
O2 + H2O + sunlight → Products

The number of molecules in 22.4 dm³ of nitrogen gas at STP is _______.

6.023 x 10²³
22.4 x 10²⁰
6.023 x 10²⁰
22.4 x 10²³

The molecular mass of an organic compound is 78. Its empirical formula is CH. The molecular formula is _______.

C₂H₄
C₄H₄
C₂H₂
C₆H₆

Which pair of species have same percentage of carbon?

HCOOCH3 and C12H22O11
CH3COOH and C2H5OH
C6H12O6 and C12H22O11
CH3COOH and C6H12O6

The mass of 1 atom of hydrogen is _______.

3.2 x 10^-24g
0.5 g
1.6 x 10^-24 g
1 g

3 g of H₂ reacts with 29 g of O₂ to yield water. Which is the limiting reactant?

none of there
H₂
O₂
H₂O

Which of the following is the value of amu?

1.57 x 10²⁴ kg
1.66 x 10²⁴ kg
1.99 x 10²³ kg
1.66 x 10²⁷ kg

Two elements, X (Atomic mass 16) and Y (Atomic mass 14) combine to form compounds A, B and C. The ratio of different masses of Y which combine with fixed mass of X in A, B and C is 1:3:5. If 32 parts by mass of X combine with 84 parts by mass of Y in B, then in C, 16 parts by mass of X will combine with _______.

42 parts by mass of Y
82 parts by mass of Y
70 parts by mass of Y
14 parts by mass of Y