21.

The radiant energy from the sun is due to :

• combustion

• chemical reaction

• nuclear fusion

• nuclear fission

Which is not a true peroxide ?

• H₂O₂

• Caro's acid

• Marshall's acid

• Thiosulphuric acid

The two isomers given below are :

• enantiomers

• diastereomers

• mesomers

• position isomers

Which of the following products are formed when SiCl₄ vapour are passed over hot Mg ?

• SiCl₂ + MgCl₂

• Si + MgCl₂

• Mg₂Si + MgCl₂

• MgSiCl₆

What is the half-life of ₆C¹⁴ , if its disintegration constant is 2.31 x 10^-4 yr^-1 ?

• 0.3 x 10⁴ yr

• 0.3 x 10³ yr

• 0.3 x 10⁸ yr

• 0.3 x 10² yr

Ni/Ni²⁺ [1.0 M] || Au³⁺ [1.0 M]/Au (where E° for Ni²⁺/Ni  is -0.25 V E° for Au³⁺/Au is 0.150 V)

Whar is the emf of the cell ?

• + 0.4 V

• - 1.75 V

• + 1.25 V

• + 1.75 V

When fluorine reacts with hot and conc. NaOH , it gives :

• Na₂O

• Na

• H₂

• O₂

In acidic medium MnO₄^2- is converted to Mn²⁺ .The quantity of electricity in faraday required to reduce 0.5 mole of MnO₄^2- to Mn²⁺ would be :

• 2.5

• 1

• 5

• 0.5

During electrolysis of water the volume of oxygen liberated is 2.24 dm³ .The volume of hydrogen liberated , under same conditions will be :

• 2.24 dm³

• 1.12 dm³

• 4.48 dm³

• 0.56 dm³

End product of the hydrolysis of XeF₆ is :

• XeOF₄

• XeO₂F₂

• XeO₃

• XeOF₃