The original amount of radioactive substance is 10 grams. After several years, 2.5 gtams of the substance is remaining. How many half-lives havr passed since the mass of the subtance was 10 grams?

A thermometer is in a beaker of water. Which statement best explains why the thermometer reading initially increases when LiBr (s) is dissolved in the water? (1) The entropy of the LiBr (aq) is greater than the entropy of the water.

What is the oxidation number of cl in naclo3

Write a chemical equation for nh4 + (aq) showing how it is an acid or a base according to the arrhenius definition.

A compound's empirical formula is ch3. if the formula mass is 30 amu, what is the molecular formula?

In one bottle you have a mixture of oxygen and hydrogen. In a second one is water. Do they have the same energy? How do you know which one is a fuel and which is not?

What characteristics of water allow it to have high surface tension?

Obtaining scientific data from a distance is called?

What is organic chemistry?

What is the total number of electrons shared in a double covalent bond between two atoms? (1) 1 (3) 8 (2) 2 (4) 4

Which method separates mixtures according to the rates their components travel through a material? yhaoo answers?