Which of the following elements is chemically similar to Oxygen?
a. flourine
b. nitrogen
c. Sulfur
d. Hydrogen
Which of the following is smallest?
a. proton
b. electron
c. neutron
d. nucleus
The number "a million trillion" can also be written as 1015
True
False
Our Milky Way galaxy contains perhaps 400 billion stars. Suppose that 0.05% (i.e., 0.0005) of these stars have planetary systems containing at least one Earthlike planet (one that could conceivably support Earthlike life). Express this number in words (thousands or millions, etc.).
a. 200 million
b. 200 thousand
c. 20 billion
d. 20 thousand
1. http://www.webelements.com/
Look for the element in the same column as oxygen, element # 8.
2. http://www.krysstal.com/subatomic.html
mass of electron, proton, neutron in a table.
3. What do you think? That looks like one thousane fifteen to me.
4. 400 billion x 0.0005 = 200,000,000.
2,000 is 2 thousand.
2,000,000 is 2 million.
200,000,000 is _____________.
1 answer
1 answer