Can someone please help me??

7. what temperature is need to just dissolve 50 g of nh4cl in 75 g of water? '

Which of the following would have less momentum than a 52 kg cheetah running at 10 m/s?

What is a substance? a. a physical property of matter b. a chemical property of matter c. an element or compound that cannot be physically separated d. characteristics used to tell the difference between mixtures