Why do different elements have different values of atomic mass?

5.2 g of HCl are dissolved in 25 mL of solution. What is the molarity?

Hexane and hexene are hydrocarbon compounds from different homologous series. the combustion of these two compounds produce different amount of soot. explain the difference based on the percentage of carbon by mass.

One mole of something consists of unit of

Hunter drew a representation of the atoms of a gas. The illustration shows atoms moving freely at high speeds.

Which of the following is the best thermal conductor? A. Stone B. Air C. Water D. Metal

After 10 years, 75 g of an original sample of 100 g of a certain radioactive isotope has decayed. the half-life of the isotope is

When 10.7 g of Al are reacted with 42.5 g of HCl, what volume of H2 will be produced at 47 C and 725 mmHg? Formula: 2Al+6HCl=2AlCl3+3H2

Increasing the temperature increases the rate of a many reactions by:

2A balloon filled with helium occupies 20.0 L at 1.50 atm and 25°C. How many moles of helium will there be in the balloon at STP? A. 22.4 moles B. 1.12 moles C. 0.0446 moles D. 0.893 moles E. 1.23 moles F. 4.55 moles

1. Which has a larger radius Ca atom or Ca+2 ion? 2. Which has a greater radius F atom or F - ion? 3. Which is the correct way of understanding the trend for Ionic radius Vs. Atomic radius?