It should be mass and speed so they are both incorrect because the height doesn’t mean much, but what matters is how heavy the object is, and how fast it’s going to go.
The acceleration is -8.89 m/s
Four Consecutive terms are written as a-3, a-1, a+1,a+3. So
Sum of Terms : 4a=28
a=7
So the terms are 4,6,8,10
Verification : 4^2+6^2+8^2+10^2
= 216
<u>Answer:</u>
2.0158 grams
<u>Explantion:</u>
We are to find the mass of the hydrogen atoms in 1 mole of water.
We know that the formula of water is: 
We can see, from the above mentioned formula, that water has 2 hydrpgen atoms.
From the periodic table, we get to know that Hydrogen has an atomic mass of 1.00794 grams.
As there are 2 atoms of hydrogen in water so
grams is the answer
Answer : The heat released by the combustion of 1.121 mol of hexane (kJ) is, 
Explanation :
The given balanced reaction is,

Given:
Moles of hexane = 0.121 mol
= -8326 kJ/mol
The negative sign indicate that the reaction exothermic or amount of heat released.
As, 1 mole of hexane released heat = 8326 kJ
So, 0.121 mole of hexane released heat = 8326 × 0.121 = 1007.446 ≈ 
Therefore, the heat released by the combustion of 1.121 mol of hexane is
.