Before a bond breaks in a chemical reaction, what happens?

A. Energy is absorbed.

B. Neutrons in the nucleus expand.

C. An atom loses its protons.

D. The products get larger.

Which element (s) is/are not balanced in this equation? MgO + 2 LiCl - - > MgCl2 + Li2O

Which of the following is an example of a hormone? Adrenaline Blood Calcium Thyroid

The mass of a sample of sodium bicarbonate is 2.1 kilograms. There are 1,000 grams in 1 kg, and 1 x 10^9 nano-grams in 1 g. What is the mass of this sample in ng?

Why do very few trees exist in a grassland ecosystem? A. not enough heat B. not enough topsoil C. not enough sunlight D. not enough precipitation

The reaction of 2h2+o2-->2H2o + heat is A exothermic B catalyze C liquid reaction D endothermic E none

How many electrons are contained in an Au3 + ion? (1) 76 (3) 82 (2) 79 (4) 197

Match the element with its number of valence electrons. Column A 1. Boron : Boron 2. Carbon : Carbon 3. Fluorine : Fluorine 4. Sodium : Sodium Column B a. 4 b. 1 c. 3 d. 7

The number of energy levels to which an electron can jump depends on the

The example of the ancient fish called a coelacanth was used to show us that science is constantly seeking new A) evidence B) ideas C) creatures D) Scientists

What factors allowed the koala population to grow beyond what their habitat could sustain?