What are columns in a periodic table usually referred to?

How does a hydroelectric power plant converts energy into energy.

The yearly amounts of carbon emissions from cars in belgium are normally distributed with a mean of 13.9 gigagrams per year and a standard deviation of 5.8 gigagrams per year. find the probability that the amount of carbon emissions from cars in belgium for a randomly selected year are between 11.5 gigagrams and 14.0 gigagrams per year. a. 0.340 b. 0.660 c. 0.167 d. 0.397

Measurements that have similar values are: a. usually accurate b. sometimes accurate c. always accurate d. never accurate