Im not 100% on these but i can try
1. A compound is made up of elements and their different atoms
2.
A. salt- compound (NaCl) is two elements Na (sodium) and Cl (chloride?)
B. Nitrogen- element its on the periodic table
C. Helium- element its on the periodic table
D. Water- compound (H2O) two elements hydrogen and oxygen
3. element, compound, compound, element
Hope this helps
The correct answer would be A "<span>A light-year is the distance light travels in a year.
This is considered a unit of distance connected to the distance that light can travel in one year. It is proved that light travels at 300,000 km per second so, in 1 year, it might travel 10 trillion km.
</span>
The components of the ball's position 
at time 
are
The ball stops 18.0 m from where it began, so that
From the second equation, we can show that the ball travels for about 
seconds, which means it was initially thrown with a horizontal velocity of
