Another alloy called nichrome contains only the elements chromium and nickel how much nickel dies it have

80 g

Explanation:

Alloy = nichrome

100 g of nichrome contains 20 g of chromium

Contains only two elements (Nickel and Chromium) hence;

Mass of Alloy = Mass of Nickel + Mass of Chromium

100 = Nickel + 20g

Nickel = 100 g - 20 g = 80 g

away from the curb

explanation:

the wheels would then hit the curb if it started to rolling, decreasing the chance of an accident.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)