Can someone please help me with these three problems ASAP .. I have to get it done right now.. I have to get it done

What is the answer for this. the correct answer only

Which of the following is the best name for mgcl2

In which situation is the acceleration of a car negative? question 5 options: a)the velocity of a car was 75 km/hr over 4 hours. b)the velocity of a car reduced from 50 km/hr over one minute. c)the velocity of a car increased from 40 km.h to 75 km/h over 15 minutes. d)the velocity of a car was 45 km/hr at 2: 00pm and at 4: 00pm its velocity was 85 km/ht.