Which of the following is an element?

a. o2

b. CaCl2

c. HPO4

d. CO2

(also i'm freshman in high school, idk why it's saying middle school)

Susan and Hannah are each riding a swing. Susan has a mass of 25 kilograms, and Hannah has a mass of 30 kilograms. Susan's swing moves with a velocity of 10 meters/second, while Hannah's swing moves with a velocity of 8.5 meters/second.

An electrical motor spins at a constant 2662.0 rpm. If the armature radius is 6.725 cm, what is the acceleration of the edge of the rotor? O 524,200 m/s O 29.30 m/s O292.7 m/s O 5226 m/s2

A ball is thrown at an angle of 40° above the horizontal at a speed of 16.0 m/s from the top of a 12.4 m tall building. What is the maximum height of the ball above the ground?

Classify which of the following is a substance: tablero salt, seawater or sand? Explain how you know.

A 2.5-L tank initially is empty, and we want to fill it with 10 g of ammonia. The ammonia comes from a line with saturated vapor at 25◦C.

Can rocks be weathered by wind and chemicals in the air

1. if you rub a neutral glass rod with silk, the silk acquires a negative charge. if you rub a neutral glass rob with a rubber rob, the rubber rod acquired a negative charge.

What's a scientific inquiry

Calculate work If force of 50 Newton's and distance is 6 meters.

What heats up hot chocolate faster? milk or water?