Natural selection requires variation between individuals. Mutations and reproduction increase genetic variation in a population. Natural selection occurs when environmental pressures favor certain traits that are passed on to offspring.
This is an acid – base reaction and this always result a salt and water
in a neutralization reaction. <span>
The salt that is formed will be calcium bromide (calcium
is located in group 2 so calcium bromide has a formula of CaBr2)
so essentially we got:
HBr + Ca(OH)2 ------> CaBr2 + H2O </span>
balancing the elements: <span>
<span>2HBr(aq) + Ca(OH)2(aq) --------> CaBr2(aq) +
2H2O(l)</span></span>
Answer: 1.5 moles
Explanation: one mole Zn uses 2 moles HCl.
1.5 moles Zn uses 3.0 mol HCl. Then Zn is a limiting reactant
And produces equal amount of H2.
Answer: B. 4 moles Fe and 3 moles CO2
Explanation:
write a balanced chemical reaction
that is FeO3 + 3 CO → 2 Fe + 3CO2
2 moles of Fe2O3 reacted with 3 x2=6 moles of Co to form Fe and CO2 therefore CO was in excess and Fe2O3 was limiting reagent.
use the mole ratio to determine the moles of each product.
that is the mole ratio 0f Fe2O3 : Fe is 1:2 therefore the moles of Fe = 2x2=4 moles
the mole ratio of Fe2CO3 : CO2 is 1: 3 therefore the moles of Co2 = 2 x3 = 6 moles
A substance cannot be a gas or a mixture. A pure<span> substance is something that occurs in nature. An element is made up of one type of atom only and cannot be split further. A compound has the combined properties of the elements from which it is made.
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