If element x has 51 protons, how many electrons does it have?

What is the chemical formula for sodium hydroxide?

A boat traveled downstream a distance of 80 mi and then came right back. If the speed of the current was 8 mph and the total trip took 5 hours and 20 minutes, find the average speed of the boat relative to the water.

Which therapy is associated with light, but not sound? A: breaking down kidney stones B: acoustically targeting the delivery of a drug C: cauterizing an incision or wound D: ablating tumors

Temperature is a measure of the average energy of particles in a substance

You are cycling along a flat road. What is the force that is pulling you downwards?

Marie and Calvin dissolved 10 grams of KNO3 in 100 grams of water at 25oC. Next they added 5 grams more.

On a frictionless air track, a blue glider with mass 0.200 kg is moving to the right with a speed of 8.00 m/s. It strikes a red glider that has mass 0.600 kg and that is initially at rest.

f a wave has a wavelength of 9 meters and a period of 0.006, what is the velocity of the wave? A. 1,200 m/s B. 1,500 m/s C. 1,800 m/s D. 1,285 m/s

Using your own words, what is Net Force? What general statement can you make about the relationship between net force and how fast an object changes it's speed?

Define valence electrons and identify the number of valence electrons in an element using periodic table.