The half - life period t_½ of a radioactive element is N years. The period of its complete decay is :

1)2 N years
2)N² Years
3)infinity
4)½ N² Years

Which of the following is correctly matched?

1) C - C bond length --- >0.077nm
2) Ionic radius of Na+ ---> 0.136 nm
3) C - Cl bond length --- >0.176 nm
4) Ionic radius of F- --- >0.095 nm

Precipitation takes place when the product of concentration of ions :

1) is less than their solubility product
2) is negligible
3) equals their solubility product
4) exceeds their solubility  product.

In an octahedral crystal field splitting, the number of orbitals pushed down in energy is 

1) 3
2) 2
3) 5
4) 0

Chalcopyrite is an ore of :

1) gallium 
2) copper
3) calcium
4) magnesium

What is the final product obtained when chlorine reacts with ethyl alcohol in KOH?

1) CHCl₃

2) CCl₃CHO

3) CH₃Cl

4) None

A 5.2 molal aqueous solution of methyl alcohol, CH₃OH is supplied. What is the mole fraction of methyl alcohol in the solution? 

(1) 0.050 

(2) 1.100 

(3) 0.190 

(4) 0.086 

Identify the least stable ion amongst the following :

1) Li⁻
2) Be⁻
3) B⁻
4) C⁻

Phenol is most easily soluble in

1. sodium carbonate solution 
2. sodium hydroxide solution 
3. dilute HCl 
4. both sodium hydroxide and dilute HCl 

When ethanol is subjected to dehydration in presence of H₂SO₄, the intermediate formed is a:

1) carbonium ion

2) carbanion

3) radical

4) carbene