Which of there is an indication that a chemical reaction has occurred?

a. freezing of substance

b. a change in color of a substance

c. melting of a substance

d. boiling of a substance

Which statement best describes ultraviolet waves? They are higher energy than X-rays. lower energy than microwaves. higher energy than visible light. lower energy than radio waves.

Ammonium hydroxide has the chemical formula NH4OH. Which statement is true about ammonium hydroxide?

How many liters of 0.775 m solution can be prepared from 55.0 g of ammonium iodide?

The only two elements in alkenes and alkynes are A. Carbon and Nitrogen B. Carbon and Hydrogen C. Oxygen and Nitrogen D. Oxygen and Hydrogen

How many grams of hydrogen are produced when 25.92 moles of hydrochloric acid (HCl) are reacted with excess copper?

Phosphorus forms a number of oxohalides, x3po, in which x may be a f, cl, or br atom. the most common of these, phosphoryl chloride, is obtained as follows:

Which statement is true about the speed of light waves in a medium? a. Depends on the temperature of the light wave b. Decreases with a decrease in density of medium c. Decreases with an increase in density of medium d.

What's a certain indicator that a molecule is polar? the molecule has a nonpolar covalent bond and the dipole is cancelled due to symmetrical arrangement of atoms the molecule has a polar covalent bond and the dipole is cancelled due to symmetrical

In the synthesis of barium carbonate from an alkali metal carbonate (M2CO3 where M is one of the alkali metals) a student generated 3.7 g of barium carbonate from 2.0 g of their alkali metal carbonate.

Give the state of matter that water is in as it moves through earths system