10. when a 13.6 g sample of a compound containing only magnesium and oxygen is decomposed, 5.4 g of oxygen is obtained. what is the percent of
magnesium in this sample?
• 5.4 g / 13.6 g * 100
• (13.6 g- 5.4g) / 13.6 g x 100
• (13.6 g- 5.4g) x 100
• 5.4g/ (13.6 g-5.4g) x 100

• (13.6 g- 5.4g) / 13.6 g x 100 is the correct option

Explanation:

Total mass of the sample containing only magnesium and oxygen is 13.6 grams. This means that the sum of the mass of oxygen and the mass of magnesium is 13.6 grams.

On decomposition of the sample, 5.4 g of oxygen is obtained. This means that the mass of magnesium that was obtained would be

13.6 - 5.4 = 8.2 grams of magnesium. Therefore, the percentage of magnesium in this sample would be

8.2/13.6 × 100 = 60.294%

(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