Acertain radioactive element has a half-life of one hour. if you start with 40.0 grams of the element at noon, how much of the radioactive element will be left at 2 p. m.?

a.) 20.0 grams
b.) 10.0 grams
c.) 5.0 grams
d.) 0.0 grams

This question is about electrolysis. metal spoons can be coated with silver. this is called electroplating. suggest one reason why spoons are electroplated?

Oxidation-reduction reactions (often called "redox" for short) are reactions that involve the transfer of electrons from one species to another. oxidation states, or oxidation numbers, allow chemists to keep track of these electron transfers. in general, one element will lose electrons (oxidation), with the result that it will increase in oxidation number, and another element will gain electrons (reduction), thereby decreasing in oxidation number. the species that is oxidized is called the reducing agent or reductant. the species that is reduced is called the oxidizing agent or oxidant. to sum up: oxidation = increase in oxidation state = loss of electrons = reducing agent reduction = decrease in oxidation state = gain of electrons = oxidizing agent part a which element is oxidized in this reaction? fe2o3+3co→2fe+3co2 enter the elemental symbol. view available hint(s) is oxidized part b which element is reduced in this reaction? 2hcl+2kmno4+3h2c2o4→6co2+2mno2+2kcl+4h2o enter the elemental symbol. view available hint(s) is reduced

What type of matter is made of only one kind of atom