Grinding quartz crystals down to produce sand is an example of a

a.

change of state.

c.

chemical reaction.

b.

chemical change.

d.

physical change.

How can the rate of a reaction be decreased? (A) lowering the amount of reactants (B) adding a catalyst (C) having more surface area (D) raising the temperature

What is the net force if you start to pull instead of pushing?

Female scientist who came to america to study starts at harvard

A golf ball and bowling ball are rolling at the same speed. Which has the greater momentum?

Since our number system is on a base-10 notation, we do not need to learn scientific notation.

The nearest large galaxy to our own is about 2.5 million light-years away. how many meters is that

An automobile travels on a straight road for 25 km at 32 km/h. it then continues in the same direction for another 25 km at 64 km/h.

Why is it important for engineers to design bumper cars safely

What must her minimum speed be just as she leaves the top of the cliff so that she will miss the ledge at the bottom, which is 1.75 m wide and 9.00 m below the top of the cliff?

Which statement describes how light behaves when it strikes a translucent material? A. Light is scattered. B. Light is transmitted. C. Light is reflected. D. Light is absorbed.