5
- hcn +
cuso4 →
type of reaction

Explanation:

The valancy of Cu = +2

SO4 = -2

CN = -1

H =+1

So when HCN and CuSO4 react Cu(CN)2 and H2SO4 are formed.

Cu(CN)2 formation :

2 CN = 2 x -1  = -2

Its should attach to +2 charge atom which is Cu

So 1 Cu and 2 CN = Cu(CN)2

Similary,

H2SO4 formation:

SO4 = -2 charge

It require +2 charge so need two H+

2 H = 2x1 = +2 charge

Hence , 1 SO4 and 2 H combine to form H2SO4

Law of conservation of mass: It states that mass can neither be created nor destroyed during a chemical reaction.

Total mass of the reactant must be equal to total mass of product.

Only those equations are balanced which follows law of conservation of mass

Count total number of atoms in the reactant and product .

The number of atoms in the product = The number of atoms in the reactant

In the given equation:

Reactant are 2HCN and CuSO4

atoms of H = 1x2=2 , C=1x2=2  , N=1x2=2 , Cu = 1, S = 1 ,O =4

Products: Cu(CN)2 and H2SO4

atoms of H =2 , S=1 , O=4 ,C = 2x1=2 , N = 2x1 =2 , Cu = 1

Hence this is balance equation

10 years is the answer