Answer:
A compound has atoms with different elements chemically combined in a completed ratio. An element is a chemical substance made of another type of atom.
The question is incomplete. Complete question is
<span>In an aqueus solution, which substance yields hydrogen ions as the only positive ions in the solution? 1)NaH 2)HCOOH 3)LiOH 4) CH3CH2OH?
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Answer: Correct answer is option 2, HCOOH
Reason:
HCOOH is a formic acid. When mixed in water, it undergoes dissociation which can be represented as
HCOOH </span>↔ HCOO- + H+
The compound NaH, will generate hydride ion (H-), while LiOH is an ionic compound, hence when dissolved in water it generated OH- ions. The compound CH3CH2OH is named as ethyl alcohol. This compound donot dissociate in aqueous medium.
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Answer:
Explanation:
N = Final mass of atom = 125 g
= Initial mass of atom = 16000 g
t = Time taken = 163.24 days
= Half life
We have the relation
The half life of the atom is .
Answer:
1/32 of the original sample
Explanation:
We have to use the formula
N/No = (1/2)^t/t1/2
N= amount of radioactive sample left after n number of half lives
No= original amount of radioactive sample present
t= time taken for the amount of radioactive samples to reduce to N
t1/2= half-life of the radioactive sample
We have been told that t= five half lives. This implies that t= 5(t1/2)
N/No = (1/2)^5(t1/2)/t1/2
Note that the ratio of radioactive samples left after time (t) is given by N/No. Hence;
N/No= (1/2)^5
N/No = 1/32
Hence the fraction left is 1/32 of the original sample.
