Answer:
E
Explanation:
100 minutes is 5 half lives ( 100 min/20 min/half life)
= (1/2 )^5
1 x 10^20 * (1/2)^5 = 3.125 x10^18 molecules
Answer:
Plant, animal, and bacteria cells are different from each other because of the parts and cell functions. A plant and animal cell has have nearly every cell parts in common, but a plant cell has chloroplast to collect sunlight to create energy or chemical energy.
Explanation:
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B, As only are metalloids or have semimetallic properties.
PH is the test of acidity or basicity of a solution. it follows the formula:
pH = pKa + log [salt] / [acid] where NaF is the salt and HF is the acid in this case.
By literature, Ka of HF is 3.5*10^-4
<span>pKa= -log(Ka)=</span><span> 3.46 </span>
<span>pH = pKa + log [NaF / [HF] </span>
4.05 = 3.46 + log [NaF / [HF]
log [NaF / [HF]<span> = 0.59
</span>
[NaF / [HF] = 3.89