QB) 9×10¹⁰
if there is 6300kg of sand and one grain of sand weighs 7×10-⁵g which is 0.00007g then we gotta turn 6300kg into grams which is: 6300000g
so now we divide 6300000g by 0.00007g which is= 90,000,000,000
and in standard form this would be 9×10¹⁰
hope this helped-have a good day bro cya)