How many moles are equal to 2.5 x 10 45 atoms of He? *

4.2 x 10 21
4 x 1021
1.5 x 10 6
1.50 x 10 69

What is an animal that lives by preying on other animals

Which of the following is an oxidation-reduction reaction? (pictured below)

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.