(1) Br2(ℓ) (3) KBr(s)
(2) K(s) (4) KBr(aq)
Answer:
KBr (aq) is a mixture.
Explanation:
Mixture is defined as the combination of two non reacting species. Let's discuss each option one by one.
a) Br₂(l):
This Bromine is not a mixture because the bracket specifying the state of Br₂ is liquid. Hence, as bromine is a liquid at room temperature, so this compound is purely Br₂.
b) KBr (s):
KBr is also present in pure form because in bracket solid is written.
c) K (s):
Potassium is also present in pure form as the bracket is specifying solid, as KBr is solid at room temperature.
d) KBr (aq):
This is a mixture of KBr and water. Because KBr being an electrolyte when dissolved in water it is hydrated as follow,
KBr (s) -----water------> K⁺ (aq) + Br⁻ (aq)
is a mixture.
Further explanation:
Mixture:
It is formed by the physical combination of two or more different substances. Mixtures do not have any fixed formula and their composition is also variable. There is retention in the properties of constituents even after the formation of mixtures.
(1)
Bromine is present in liquid in its pure state. The “l” written in the parenthesis after denotes its physical state which is the same as that of its pure form. So it is not a mixture.
(2) K (s)
Potassium is present in solid in its pure form. The “s” written in the parenthesis after K describes its physical state which is the same as that of its pure form. So it is not a mixture.
(3) KBr (s)
It is an ionic salt which is solid in nature. The “s” written in the parenthesis after KBr denotes its physical state which is the same as that of its pure form. So it is not a mixture.
(4) KBr (aq)
The “aq” written in the parenthesis after KBr indicates that it is present in the aqueous phase. This means it is formed by the combination of KBr and water so it is a mixture.
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Answer details:
Grade: High School
Chapter: Elements, compounds, and mixtures
Subject: Chemistry
Keywords: mixture, physical combination, substances, fixed formula, variable, composition, retention, properties, Br2, K, KBr.
water
B.
uranium
C.
sunlight
D.
wind
Half life of the given radioactive substance after 1000 years is 500 years.
Half -life of a substance is defined as the time which is required for half of the quantity of a radioactive substance to get decayed.It is a term which is used in nuclear chemistry for describing how quickly unstable atoms undergo radioactive decay into other nuclear species by emitting particles or the time which is required for number of disintegrations per second of radioactive material to decrease by one half of its initial value.
For the given problem, T=1000 years and N=25% of N°
where T=time period , N=amount of quantity after decay ,N°= initial quantity.
Here,N=25% of N°
N=25/100 N°=N°/4
N°/4=N°/2
n=2
∵nt=T
So. 2t=1000
t=500 years.
Hence, the half-life of a substance is 500 years.
Learn more about half-life,here:
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