71. Which one of the following statements is incorrect ?
A. All elements are homogeneous system
B. Compounds made up of a number of elements are heterogeneous.
C. A mixture is not always heterogeneous
D. Smoke is a heterogeneous mixture.
Answer : Option B
72. A balanced chemical equation is in accordance with
A. Avogadro’s law.
B. Law of constant proportions
C. Law of conservation of mass
D. Law of gaseous volumes.
Answer : Option C
73. The atomic weights of two elements X and Y are 20 and 40 respectively. If ‘a’ gm of X contains ‘b’ atoms, how many atoms are present in ‘2a’ gm of Y ?
A. b
B. a
C. 2b
D. a/2
Answer : Option A
Explanation :
No of moles of X =
No of moles of Y =
74. If the components of air are
75. Calculate the molarity of a solution obtained by mixing 50mL of 0.5M
A. 0.375M
B. 0.35M
C. 0.045M
D. 0.45M
Answer : Option B
Explanation :
→ No.of moles of 0.05L
→ No.of moles of 0.075L
Total vol = 0.05L + 0.075L = 0.125L
76. Which of the following has the highest normality ?
77. In an experiment, 4 gm of
A. 1
B. 2
C. 3
D. 4
Answer : Option C
Explanation :
→ 1 Mol
→ Now, (2 x 56 +16x) gm of oxide = 112 gm metal
→ But
Match the following
Column - I Column - II
(i) femto (P)
(ii) yotta (q)
(iii) giga (r)
(iv) atto (s)
A. i - q, ii - p, iii - r, iv - s
B. i - s, ii - q, iii - p, iv - r
C. i - q, ii - s, iii - p, iv - r
D. i - r, ii - s, iii - p, iv - q
Answer : Option C
79. The total number of atoms of all elements present in mole of ammonium dichromate is
A. 19
B.
C.
D.
Answer : Option C
Explanation :
→ Molecular formula of ammonium dichromate is
80. 0.32 gm of a metal on treatment with an acid gave 112 mL of hydrogen at STP. Calculate the equivalent weight of the metal