How and why - Why does ice float on water

Whats a chemical change

H, N, Si, Al, Mg, O a) identify the two elements which react together to form a molecule with the same shape as methane molecule. b) Identify the two elements which form an ionic compound with a formula of type X2Y3, where X is a metal.

Which stage of the cell cycle usually takes the longest?

Which component of air enables plants to synthesise their food by photosynthesis?

When does a change in energy occur? 1. In some physical changes, but not all. 2. In every physical change, but not in a chemical change. 3. In every chemical or physical change.

Complete and balance the molecular equation, including phases, for the reaction of aqueous ammonium bromide, nh4br, and aqueous lead (ii) acetate, pb (c2h3o2) 2.

A magnesium atom has 2 valence electrons in its third shell. Which is a TRUE statement about what happens when it forms an ion? A. It will be an anion. B. It will have more electrons than protons. C.

What scientific discoveries led to changes in Dalton's atomic theory?

What does berkelium react with

Classifying living things