Question

I don't unerstand what I'm supposed to do for these

Answer 1

You just need to multiply the terms and transform to kj by dividing by 1000
1) 10.4kj
2) 14.5 kj 
3) 44.8 kj
4) 1.04 kj

and there you go.

Answer 2

Explanation:

1000 J= 1 kJ

1. Heat = mass × c × Temperature change

=$175 g\times 0.79 J/g^oC\times 75^oC=10,368.75 J=10.36878 kJ\approx 10.4 kJ$

2.Heat = mass × c × Temperature change

=$352 g\times 1.65 J/g^oC\times 25^oC=14,520 J=14.520 kJ\approx 14.5 kJ$

3.Heat = mass × c × Temperature change

=$268 g\times 4.18 J/g^oC\times 40^oC=44,809.6 J=44.8096 kJ\approx 44.8 kJ$

4.Heat = mass × c × Temperature change

=$74 g\times 0.21 J/g^oC\times 67 ^oC=1,041.18 J=1.04118 kJ\approx 1.04 kJ$