Number of moles of K₂Cr₂O₇ reduced by one mole of Sn²⁺: 

• $\frac{1}{3}$

• 3

• $\frac{1}{6}$

• 6

Radioactive isotope of hydrogen is :

• Uranium

• Deuterium

• Tritium

• None

Electronk configuration of hydride ion is :

• 1s^o

• 1s¹

• 1s²

• 1s¹2s¹

Suitable condition for melting of ice :

• high temp. and high pressure

• high temp. and low pressure

• low temp. and low pressure

• low temp. high pressure

Least ionised salt is :

• KCl

• AgCl

• MgCl₂

• CaCl₂

16.

Number of unpaired electrons in O₂ molecule is :

• zero

• one

• two

• four

In exothermic reaction heat is :

• given out

• absorbed

• not involved

• given out or absorbed

Element having maximum affinity is :

• F₂

• Cl₂

• Br₂

• I₂

Bond order in benzene is :

• 1

• 2

• 1.5

• none of these

Element having maximum ionization energy :

• Na

• Li

• K

• Rb