Multiple Choice QuestionsIn the hardening stage of plaster of paris, the compound formed is
CaSO4
Orthorhombic CaSO4.2H2O
CaSO4.2H2O
Monoclinic CaSO4.2H2O
Sodium is heated in air at 300°C to form X. X absorbs CO2 and forms Na2CO3 and Y. Which of the following is Y ?
H2
O2
H2O2
O3
In which of the following reactions, MgO is not formed?
Mg + CO2 →
Mg + dil. HNO3 →
Mg + NO
Mg + B2O3
Which of the following is not correct ?
Ammonia is used as refrigerant
A mixture of Ca(CN)2 and C is known as nitrolim.
A mixture of Ca(H2PO4)2 and CaSO4 .2H2O is known as superphosphate of lime.
Hydrolysis of NCl3 gives NH3 and HOCl.
Observe the following statements:
I. Bleaching powder is used in the preparation of chloroform.
II. Bleaching powder decomposes in the presence of CoCl3 to liberate O3.
III. Aqueous KHF2 is used in the preparation of fluorine.
The correct combination is :
I, II and III are correct
Only II is correct
Only I and III are correct
Only I and II are correct
Which of the following statements are correct for alkali metal compounds ?
(i) Superoxides are paramagnetic in nature.
(ii) The basic strengths of hydroxides increases down the group.
(iii) The conductivity of chlorides in their aqueous solutions decreases down the group.
(iv) The basic nature of carbonates in aqueous solutions is due to cationic hydrolysis.
(i), (ii) and (iii) only
(i) and (ii) only
(ii), (iii) and (iv) only
(iii) and (iv) only
B.
(i) and (ii) only
Among the gievn statements, statement (i) and (ii) are correct. Other can be corrected as-
(iii) The conductivity of alkali metal chlorides in their aqueous solution increases on moving down the group because in aqueous solution alkali metal chlorides ionise to give alkali metal ions. On moving down the group the size of alkali metal ion increases, thus degree of hydration decreases, due to this reason their conductivity in aqueous solution increases on moving down the group.
(iv) M2CO3
+ 2H2O → H2CO3 + 2OH-
CaOCl2 + H2O → Ca(OH)2 + X
X + CH3CHO → Y
Y + Ca(OH)2 → CHCl3
What is 'Y'?
CH3CH(OH)2
CH2Cl2
CCl3CHO
CCl3COCH3
Among the following, which is water insoluble?
Sodium fluoride
Potassium fluoride
Beryllium fluoride
Magnesium fluoride
Assertion (A) - K, Rb and Cs form superoxides.
Reason (R) - The stability of the superoxides increases from K to Cs due to decrease in lattice energy.
The correct answer is
Both (A) and (R) are true and (R) is the correct explanation of (A).
Both (A) and (R) are true but (R) is not the correct explanation of (A).
(A) is true but (R) is not true.
(A) is not true but (R) is true.
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