Which of these pairs of elements have the same number of valence electrons?

hydrogen (H) and helium (He)

sodium (Na) and potassium (K)

carbon (C) and oxygen (O)

boron (B) and beryllium (Be)

What is the volume, in ml, of 0.183 mol NH3? (at STP).

If you roll a ball down a ramp, which factor will have the greatest effect on the amount of friction created? (a) Force applied to the ball (b) Speed of the ball (c) Texture of the surface (d) Weight of the ramp

What type of circuit is it when there are 2 lights in a circuit but only one is working?

How many milliliters of 0.260 m na2s are needed to react with 35.00 ml of 0.315 m agno3?

Which of an atoms electrons are involved in chemical reactions

1. Which of the following best describes an example of pure chemistry? a) testing the effects of lower concentrations of a drug on humans b) studying chemicals containing carbon c) developing a cure for osteoporosis d) finding an antidote for a new

Problem 1: For which of the following activities might you want to hire a chemist? A. building a garage B. testing a sample of water from a well C. finding a comet D.

Why do most living things need food water and the ability to get rid of waste?

What is the effect of adding more water to the following equilibrium reaction? CO2 + H2O - > 2H2CO3

What aldol product is formed when two molecules of butanal react together in the presence of base?