THE S-BLOCK ELEMENTS Quiz-7

Chemistry Aptitude Quiz

Dear Readers,

IIT JEE exam which consists of JEE Main and JEE Advanced is one of the most important entrance exams for engineering aspirants. The exam is held for candidates who are aspiring to pursue a career in the field of engineering and technical studies. Chemistry is important because everything you do is chemistry! Even your body is made of chemicals. Chemical reactions occur when you breathe, eat, or just sit there reading. All matter is made of chemicals, so the importance of chemistry is that it's the study of everything..

Q1. Reagent used as fixer in photography

•   AgBr
•  AgNO3
•  Na2S2O3.5H2O
•  Both a and c

Solution
(c) part
Na2S2O3 (as fixer) dissolves unreacted AgBr as
2Na2S2O3+AgBr→Na3 [Ag(S2O3)2]+NaBr

Q2.The charage/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizing power of cationic species; K^+,Ca^(2+),Mg^(2+),Be^(2+)?

•   Mg^(2+)<Be^(2+)<K^+<Ca^(2+)
•  Be^(2+)<K^+<Ca^(2+)<Mg^(2+)
•  K^+<Ca^(2+)<Mg^(2+)<Be^(2+)
•  Ca^(2+)<Mg^(2+)<Be^(2+)<K^+

Solution
(c)

Q3.  NaNO3 is converted to KNO3 by following reaction NaNO3 (aq)+KCl(aq)⇌KNO3 (aq)+NaCl(s) In the above equilibrium, which is least soluble in hot water?

•   NaNO3
•  KCl
•  KNO3
•  NaCl

Solution
(d) part

Q4. Which are true statements about s-block elements?

•  Metals are obtained by the electrolysis of fused chlorides
•  Only one type of valency, +1 for I A and +2 for II A, is show
•  Oxides are basic except BeO
•  All of the above are correct statements

Solution
(d) part

Q5.Suboxide of Rb has the formula

•  RbO2
•  RbO3
•  Rb2O2
•  Rb6O

Solution
  d part

Q6. 1 mole of a substance (X) was treated with an excess of water. 2 moles of readily combustible gas were produced along with solution which when reacted with CO_2 gas produced a white turbidity. The substance (X) could be

•   Ca
•  CaH2
• Ca(OH)2
•  Ca(NO3)2

Solution
(b) part

Q7. Among Na^+,Na,Mg and Mg^(2+) the largest particle is

•  Mg+2
•  Mg
•  Na
•  Na+

Solution
(c)
Mg^(2+) < Na^+ Mg <Na

Q8.

∆G° values (kJ mol^(-1)) for the following cases are given below
MCO_3 →MO + CO_2
Mg -1028.2-568.9-394.4
Ca -1129.2-603.4
Ba-1134.4-520.4
In which case decomposition of MCO_3 is most spontaneous?

•  MgCO3
•  TCaCO3
•  BaCO3
•  Equally in all cases

Solution
(a)
∆G° (Mgsalt) =-568.9-394.4 (-1028.2) =-963.3+1028.2=64.9 kJ
∆G°(Ca salt) =-603.4-394.4-(-1129.2) =-997.8+1129.2=131.4
∆G°=-520.4-394.4-(-1134.4) =-914.8+1134.4=219.6
∆G° of MgCO_3 is minimum, thus decomposition of MgCO_3 is most feasible

Q9.Nitrolim is a

•  Mixture of calcium carbide and nitrogen
•  Mixture of calcium cyanamide and carbon
•  Mixture of calcium cyanide and carbon
•  Mixture of NH4CN and CaCN

Solution
(b)Part

Q10. Select the correct statement(s)

•  Stability of peroxides and superoxides of alkali metals increases with increase in size of the metal ion
•  NaOH does not form hydrated salt
•   Increase in stability in (a) is due to stabilization of large anions by larger cations through lattice energy effects
• The low solubility of LiF is due to its high lattice energy whereas low solubility of CsI is due to smaller hydration energy

Solution
(b) part