Which of the following always occurs in a

chemical reaction?

A) a gas is given off.

B) a solid is produced,

C) a new substance is produced.

D) a colour change takes place.

How many particles are in a sample of KNO3?

List the gases h2o, he, hcl, brf, and no2 in order of increasing average molecular velocity at 25◦c. 1. rates of effusion: no2 < hcl < brf < he < h2o 2. rates of effusion: brf < no2 < hcl < h2o < he 3. rates of effusion: h2o < no2 < he < brf < hcl 4.

Which of the following is true about a change from a solid to a liquid? The particles speed up. The particles slow down. The particles remain at the same energy level. The particles get closer together.

What is the approximate pH of a 0.06 M solution of CH3COOH (given that Ka = 1.78 x 10-5) ? A. 1 B. 3 C. 6 D. 7 E. 9

A scientist conducts a experiment to determine

What kind of reaction is ca (s) + h3po4 (aq) ca3 (po4) 2 (s) + h2 (g)

In the teapot dome scandal, what did the secretary of the interior albert fall lease

A Material made of equal parts is called what? A. Atom, B. Pure substance, C. Mixture

Part C Why are dichotomous keys useful in classifying a new species?

2. How is the frequency of a wave determined?