<span>NaCl (halite) or KCl (sylvite) </span>
Answer:
Freezing and condensation
Explanation:
Because they are exothermic, they release energy
Answer: whole number ratios
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass. It can be decomposed into simpler constituents using chemical reactions. Example: water 
Thus the ratio of hydrogen and oxygen is 2: 1 and is a whole number ratio.
Answer:

Explanation:
When adding or subtracting values, you must round your answer to the same "place" as the measurement with its last significant figure furthest to the left.
That is, you round off to the same number of decimal places as the measurement with the fewest decimal places.

The measurement of 28.1 cm has one digit after the decimal point, so you round the sum to have only one digit to the right of the decimal.
However, the number to be dropped (51) is greater than 5 with only zeros or nothing following the 5.
You must round up the answer. You increase the last significant digit by one.

Two substances that have the same number of moles of representative particles always have:
none of these are correct