49. If an atom contains 13 protons, then it has (2.4)

a. 13 electrons. b. 26 electrons. c. 13 neutrons.

d. 26 neutrons,

What causes charges to move in a circuit? a. voltage b. energy c. electricity d. magnetism

According to the collision theory, all collisions do not lead to reaction. Which choice gives both reasons why not all collisions between reactant molecules lead to reaction? 1.

A skateboarder, just learning to use a half pipe as shown below, drops in off the top of one side. She stands straight as she skates down the one side and up the other. She expected to get to the top of other side but didn't make it.

Which of the following is a star early in its life? A. Protostar B. Main sequence star C. White dwarf D. Red giant

What is the function of a transformer? Why is this done?

Which of the following is a vector quantity (a) mass (b) speed (c) time (d) acceleration

A 85-kg astronaut (including spacesuit and equipment) is floating at rest a distance of 11 m from the spaceship when she runs out of oxygen and fuel to power her back to the spaceship. She removes her oxygen tank (3.

Find the specific gravity of the rose quartz. Specific gravity = density of of water. What are the units for specific gravity?

A ball of mass 5.0kg is lifted off the floor a distance of 1.7m. 1. What is the change in the gravitational potential energy of the ball? 2. Now you release the ball from rest, and it falls to the floor.

What is the device to break a circuit called?