Which element is found in nature only in compounds? A. sodium B. helium C. oxygen D. nitrogen

There are 18 periods in the periodic table. Which answer choice rewords the false statement so it is true?

Can sound travel in places where there is no matter?

What is the element named after the man that put the first periodic table together?

Gasoline has an octane number of 70. What is the percent isooctane to the percent heptane in this sample of gasoline?

What is the process in which trace amounts of other elements are added to a material to make it a semiconductor? a. doping c. ionization b. salting d. conduction

A living thing that cannot make its own food and must eat other living things for energy

Which best explains why astronauts appear weightless when they are in a space shuttle orbiting Earth? • They are falling toward Earth at the same rate as the space shuttle.

If increase the amplitude how does the velocity change? (No google)

What is the result of multiplying (2.5 * 1010) * (3.5 * 10-7) ? Use the correct number of significant digits.

What is 0.002353 to two significant figures