D. Hydrogen chemical bonds are found within water molecules.
The excess reactant when 4.35 g of hydrogen reacts with 30.75g of hydrogen iodide is hydrogen
<h3>calculation</h3>
write the equation for the reaction
H2(g) + I2 (g) → 2HI (g)
find the mole of each reactant
moles = mass/molar mass
moles of H2= 4.35 g/2 g/mol= 2.175 moles
moles o I2 = 30.75 g/ 254 g/mo=0.1211 moles
0.1211 moles of I2 reacted with 0.1211 moles of H2 but there are more moles of H2 there Hydrogen was in excess
Answer: -
(a) 1.54 x 10² pm
(b) 1.3 x 10⁶ is the number of carbon atoms could be aligned side by side in a straight line across the width of 0.2 mm.
Explanation: -
1 å = 10² pm
Diameter of a carbon atom = 1.54 å = 1.54 x 10² pm
1 mm = 10⁹ pm
Total distance = 0.2 mm = 0.2 x 10⁹ pm
Number of carbon atoms could be aligned side by side in a straight line across the width = Total distance / Diameter of a carbon atom
= 
= 1.3 x 10⁶
Answer:
C
Explanation:
If the enthalpy change (i.e. Δ<em>H</em>) of a reaction is negative, then the reaction releases heat and is hence exothermic.
Hence, our answer is C.
Conversely, if Δ<em>H</em> is positive, the reaction absorbs heat and is endothermic.
Δ<em>H</em> tells us nothing about the speed of the reaction.
While Δ<em>H</em> influences free-energy change (Δ<em>G</em> = Δ<em>H</em> - <em>T</em>Δ<em>S</em>), we cannot predict the sign of Δ<em>G</em> given only Δ<em>H </em>(recall that a reaction is spontaneous if Δ<em>G</em> < 0).
