Oxygen and silicon makes up what percentage of the Earth crust. A) 57% B) 98.5% C) 75% D) 50%

answer

the answer is C

explanation

this is because the oxygen makes up 46.1%of the earth's surface while silcon is 28.5% and the question says "what makes up" which means you should add them and it becomes 74.6% which Is approximately 75%

it is a solid

explanation:

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied