Discussion Forum

1)

 When copper is treated with a certain concentration of nitric acid, nitric oxide and nitrogen dioxide  are liberated in equal volumes according to the equation,

$xCu+yHNO_{3}\rightarrow Cu(NO_{3})_{2}+NO+NO_{2}+H_{2}O$

 the coefficient of x and y are respectively

Answer:

Option B

Explanation:

 Balanced equation

$3Cu+8HNO_{3}\rightarrow 3Cu(NO_{3})_{2}+2NO+4H_{2}O$....(i)

 $Cu+4HNO_{3}\rightarrow Cu(NO_{3})_{2}+2NO_{2}+2H_{2}O$

 Here NO and NO₂ are evolved in equal volumes, hence on adding Eqs. (i) and (ii)

$4Cu+12HNO_{3}\rightarrow 4Cu(NO_{3})_{2}+2NO+2NO_{2}+6H_{2}O$

or  

$2Cu+6HNO_{3}\rightarrow 2Cu(NO_{3})_{2}+NO+NO_{2}+3H_{2}O$

 Hence, coefficients x and y of Cu  and HNO₃ are 2 and 6 respectively