In case of any doubt please fee free to discuss further.
1. Whenever any amount is received from the shareholder, as a rule first that amount is applied towards whatever is due towards share capital, balance amount is applied towards share capital. In Hari's case, excess application money of Rs.720 was transferred to Share Allotment A/c. Amount due from Hari on account of share allotment consisted of Rs.600 Share Capital and Rs.600 towards Security Premium. So out of Rs.720, first Rs.600 is apportioned towards Share Capital and balance of Rs.120 is apportioned towards Security Premium.
2. One thing you must remember as per Sec. 52 of the Companies Act, 2013 Security Premium can be used for certain purposes. The Security Premium which the company has received can be used for the purposes mentioned in Sec. 52. Hence the Security Premium received cannot be transferred to Share Forfeiture A/c because Share Forfeiture A/c can be used for giving discount on reissue of shares and this is not one of the purposes mentioned in Sec. 52. Security Premium A/c which is not received is reversed, for example Rs.480 which is not received is reversed. Always remember only that amount which has been received on account of Share Capital can be forfeited and amount received on account of Security Premium is never transferred to Share Forfeiture A/c.
3. Total number of forfeted shares is 1500 (600+900). Out of these 1500 shares only 1200 shares have been included. The question states that reissued shares include all the shares of Mohan. This means out of 600 shares of Hari, 300 shares have been issued and balance 300 shares have not been issued. Due tos this there must be a balance of Rs.1800 (300 x 6) left in the Share Forfeiture A/c. Actually we have to transfer the profit on reissuue of 900 shares to Capital Reserve.