When two oppositely charged sols are mixed, coagulation takes place due to neutralization. So (i) is wrong.

If there are similar charges on colloidal particles, neutralization does not take place and the colloid becomes stable.so (ii) is correct.

When dispersed phase is added in excess, it forms a separate layer and thus the emulsion gets destabilized. So (iii) is also wrong.

Brownian movement helps to counter the force of gravity acting on colloidal particles and thus don’t allow to settle them down. Therefore, option (iv) is also correct.