MHT CET 2018 :: Chemistry :: General questions

• Chemistry - General questions

 What is the oxidation number of gold in the complex [AuCl4]^1- ?

Answer:

Explanation:

 Let x be the oxidation number of gold (Au) in the complex [AuCl₄]^-1

 $\therefore$     x+4(-1)=-1

 $\Rightarrow$    x=-1+4

 $\Rightarrow$    x= +3

Hence, the oxidation number of gold is +3

Which among the following metals crystallise as a simple cube?

Answer:

Explanation:

 Polonium is a radioactive element having two metallic allotropic forms; $\alpha$ -form and $\beta$-form. Out of these two forms, $\alpha$-Po form crystallises as a simple cubic crystal. Copper and gold crystallise in face-centred cubic crystal and iron crystallises in body centred cubic crystal.

Identify the element that forms amphoteric  oxide

Answer:

Explanation:

Zn(zinc)  element  of forms amphoteric oxide  .i,e, ZnO. This oxide reacts with both acids and bases, exhibiting a dual behaviour. They show characteristics of both acidic as well as basic oxides

 Following reactions are given by ZnO

$ZnO+2HCl\rightarrow ZnCl_{2}+H_{2}O$
$ZnO+2NaOH\rightarrow Na_{2}ZnO_{2}+H_{2}O$

 Note: Among oxides, CO is neutral, CaO is basic and SO₂ is acidic in nature

During galvanisation of iron, which metal is used for coating iron surface?

Answer:

Explanation:

 The process of coating iron objects with a thin layer of zinc is called galvanisation.It is done by dipping the object in molten zinc. this method is used to prevent  corrosion on iron objects

A certain reaction  occurs in two steps as 

(i)  $2SO_{2}(g)+2NO_{2}\rightarrow 2SO_{3}(g)+2NO(g)$

(ii)  $2NO(g)+O_{2}(g)\rightarrow 2NO_{2}(g)$

 in the reaction,

Answer:

Explanation:

Given:

Step I: $2SO_{2}(g)+2NO_{2}\rightarrow 2SO_{3}(g)+2NO(g)$

Step II: $2NO(g)+O_{2}(g)\rightarrow 2NO_{2}(g)$

 an intermediate formed in the reaction is not a part of overall reaction.

 Net reaction: $2SO_{2}(g)+O_{2}(g)\rightarrow 2SO_{3}(g)$

 As, NO(g)  formed in first elementary step is neither a reactant  nor a product  in the net reaction. it is formed in one elementary step and consumed in the next step. Thus, NO(g)  acts as an intermediate

• Chemistry - General questions