s-block-quiz-3

S-Block Quiz-3

Dear Readers,

The one subject in NEET which is candidates who can easily attain good marks is Chemistry. That's the reason, often, one doesn’t pay notice and choose to compromise it. But if one wants to rank above others, the tip is to be thorough with NEET chemistry concepts. The understanding of reactions and definite basic understanding is what requires major attention in Chemistry but once done it only gets simpler from there. The main focus on the to-do list should be on getting a hang of the NCERT syllabus of NEET chemistry..

Q1. A solution of KOH in water is called:

•  Potash lye
•  Soda lye
•  Salt cake
•  None of these

Solution
(a) KOH(aq.) is potash lye; NaOH(aq.) is soda lye; anhydrous Na₂ SO₄ is salt cake.  

Q2.Iceland spar is:

•  CaSiO₄
•  CaCO₃
•  CaF₂
•  NaAIF₆

Solution

(b) CaCO₃ is called Iceland spar.

Q3. Which of the following is correct? 

•  In the Castner’s process of sodium extraction, NaCl is used as an electrolyte.
•  Sodium reduces CO₂ to carbon.
•  Mg reacts with cold water and liberate hydrogen gas.
•  Magnalium is an alloy of Mg and Zn.

Solution
(b) Alkali metals are electropositive, hence they can reduce 

CO₂. 4Na+CO₂ →2Na₂ O+C

Q4. Flash bulbs contain wire or foil of Mg packed in an atmosphere of:

•  SO₃
•  O₂
•  Air
•  N₂

Solution
(b) 2Mg+O₂⟶2MgO+Light

Q5.Superphosphate of lime is a mixture of:

•  Primary calcium phosphate and Epsom
•  Primary magnesium phosphate and Epsom
•  Primary magnesium phosphate and gypsum
•  Primary calcium phosphate and gypsum

Solution
  (d) It is a fact.  

Q6. Na₂ SO₃ and NaHCO₃ may be distinguished by treating their aqueous solution with:

•  Litmus solution
•  Dil. Acid
•  MgO
•  MgSO₄

Solution
(d) Na₂ CO₃ reacts with MgSO₄ to give basic magnesium carbonate. 

2MgSO₄+2Na₂ CO₃+H₂ O⟶MgCO₃∙Mg(OH)₂+2Na₂ SO₄+CO₂  

Q7.Which one of the following electrolytes is used in Down’s process of extracting sodium metal?

•  NaCl+KCl+KF
•  NaCl
•  NaOH+KCl+KF
•  NaCl+NaOH

Solution

(a) Sodium metal is manufactured by the electrolysis of fused sodium chloride mixed with KCl and KF. On electrolysis ;

 At iron cathode

 Na⁺+e^- ⟶Na (s)(metallic sodium) 

At graphite anode : 

 2Cl^- ⟶Cl₂ (g)+2e^- 

NaCl melts at 800℃. 

 It is difficult to attain and maintain its melting point. So, KCl and KF are mixed to lower the melting point of NaCl to about 600℃. KCl and KF are themselves not electrolysed under the voltage conditions used for sodium.

Q8.Magnesium wire burns in the atmosphere of CO₂ because:

•  Magnesium acts as an oxidizing agent
•  Magnesium has 2 electrons in the outermost orbit
•  Magnesium acts as a reducing agent and removes oxygen from CO₂
•  None of the above

Solution
(c) Mg is more powerful reductant than carbon.  

Q9.Which of the following hydroxides is amphoteric in nature?

•  Be(OH)₂
•  Mg(OH)₂
•  Ca(OH)₂
•  Ba(OH)₂

Solution

(a) Be(OH)₂ has minimum basicity and has amphoteric character as it dissolves both in acid and in alkali. 

 Be(OH₂ )+2HCl ⟶BeCl₂+2H₂ O 

 Be(OH₂ )+2NaOH ⟶Na₂ BeO₂+2H₂ O

Q10. Which represents nitrolime?

•  CaCN₂+C
•  CaC₂+N₂
•  Ca(CN)₂+Ca(NO₃ )₂
•  None of these

Solution

(a) Nitrolim is CaCN₂+C.