Which of the following is not the same as 2.97 milligrams?
a)0.297 cg
b)0.00297 g
c) 0.297 kg

Answer : The (C) 0.0000297 kg is not the same as 2.97 mg.

Explanation :

The conversion used for mass from milligram to centigram is:

The conversion used for mass from milligram to gram is:

The conversion used for mass from milligram to kilogram is:

As we are given that the mass 2.97 mg. Now we have to determine the mass in cg, g and kg.

Mass of 'cg' :

Mass of 'g' :

Mass of 'kg' :

Hence, from this we conclude that, 0.0000297 kg is not the same as 2.97 mg.

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%

(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