Which method of testing substances is a sure way to identify a chemical reaction? a. change in color b. formation of bubbles c. change in density d. increase in temperature e. solubility in water

An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. the company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 72 miles per hour with a standard deviation of 2.2 miles per hour. another sample of 18 cars driven by women on the same highway gave a mean speed of 68 miles per hour with a standard deviation of 2.5 miles per hour. assume that the speeds at which all men and all women drive cars on this highway are both approximately normally distributed with unknown and unequal population standard deviations.

What will a positive and a negative charge do if they are separated from each other?

Two balls, each with a mass of 0.5 kg, collide on a pool table. is the law of conservation of momentum satisfied in the collision? explain why or why not