s-block-quiz-1

S-Block Quiz-1

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. Which of the following compounds has the lowest melting point?

•  CaF₂
•  CaCl₂
•  CaBr₂
•  CaI₂

Solution
(d) CaI₂ has maximum covalent character due to large size of anion and possesses lowest lattice energy. Thus melting point is lowest.  

Q2.In India, at the occasion of marriages, the fireworks used give green flame. Which one of the following radicals may be present?

•  Na
•  K
•  Ba
•  Ca

Solution

Q3. Molten NaCl conducts electricity due to the presence of: 

•  Free molecules
•  Free electrons
•  Free ions
•  Atoms

Solution
(c) Molten NaCl has Na⁺ and Cl^- ions.

Q4. Sedimentary rocks laid down under water mainly contain:

•  CaO
•  Ca(OH)₂
•  CaCO₃
•  CaSO₄

Solution
(c) It is a fact.

Q5.Which alkali metal emits largest wavelength in the flame test?

•  Na
•  Li
•  K
•  Cs

Solution
  (b) Li has highest ionisation enthalpy and use larger energy of flame and thus emits red light (longer wave length).  

Q6. The ionic conductances of following cations in a given concentration are in the order

•  Li⁺<Na⁺<K⁺<Rb⁺
•  Li⁺>Na⁺>K⁺>Rb⁺
•  Li⁺<Na⁺>K⁺>Rb⁺
•  Li⁺=Na⁺<K⁺<Rb⁺

Solution
(a) Conductance of an ion is dependent upon its size – as follows :

 Ionic conductance ∝1/(ionic size) 

Thus, ionic conductance in aqueous solution increases in the order- Cs⁺<Rb⁺<K⁺<Na⁺<Li⁺  

Q7.Phosphine, acetylene and ammonia can be formed by treating water with

•  Mg₃ P₂,Al₄ C₃,Li₃ N
•  Ca₃ P₂,CaC₂,Mg₃ N₂
•  Ca₃ P₂,CaC₂,CaCN₂
•  Ca₃ P₂,Mg₂ C,NH₄ NO₃

Solution

Q8.A fire of lithium, sodium and potassium can be extinguished by

•  H₂ O
•  Nitrogen
•  CO₂
•  Asbestose blanket

Solution
(c) ∵ Carbon dioxide does not help in burning and it reacts with alkali metals to form carbonates. 

∴CO₂ is used to extinguish fire of lithium, sodium and potassium.  

Q9.Sodium thiosulphate is a

•  Reducing agent
•  Oxidising agent
•  Complexing agent
•  Bleaching agent

Solution

(a) The presence of excess of sulphur makes sodium thiosulphate a useful reducing agent. 

 2Na₂ S₂ O₃+I₃ →Na₂ S₄ O₆+2NaI This reaction is applied in volumetric estimation of iodine. In this reaction sodium thiosulphate acts as a reducing agent.

Q10. Which of the following alkali metal ion in aqueous solution is the best conductor of electricity?

•  Li⁺
•  Na⁺
•  Cs⁺
•  K⁺

Solution

(c) Cs⁺ (aq) is the smallest alkali metal cation in solution state.