Answer :
Total mixture weight equals the weight of all the components added together:
0.8g salt + 1.3g SIO2 + 2.5g NH4Cl = 4.6g total
To find the percent composition of the mixture, divide the weight of each component in the mixture by the total weight of the mixture and multiply by 100.
For salt: 0.8g / 4.6g = 0.1739 * 100 = 17.39% salt
For SIO2: 1.3g / 4.6g = 0.2826 * 100 = 28.26% SIO2
For NH4Cl: 2.5g / 4.6g = 0.5435 * 100 = 54.35% NH4Cl