Answer : The correct option is, (D)
Explanation :
Option A reaction : 
It is a combustion reaction. A reaction in which a hydrocarbon react with the oxygen to give product as carbon dioxide and water.
Option B reaction : 
It is a combination reaction. A reaction in which the two or more reactants react to give a product.
Option C reaction : 
It is a decomposition reaction. A reaction in which a reactant decomposes to form two or more products.
Option D reaction : 
It is a single displacement reaction. It is a reaction in which the more reactive element displace the less reactive element. In this reaction, most reactive element chlorine displaces the less reactive element bromine.
Hence, the correct option is, (D)
Answer:
=> 11. <u>d.</u> Moon
The moon is not a light source because it does not emit its own light.
=> 12. b. <u>The</u> <u>light</u> is <u>refracted</u>.
13. What is the substance produced by a chemical reaction called?
=> b. Product
Answer:
Explanation:
There are eight isotopes of lawrencium, and they are all radioactive,
I will do the calculation for ²⁶²Lr, which has a half-life of 3.6 h.
Let A₀ = the original amount of lawrencium.
The amount remaining after one half-life is ½A₀.
After two half-lives, the amount remaining is ½ ×½A₀ = (½)²A₀.
After three half-lives, the amount remaining is ½ ×(½)²A₀ = (½)³A₀, and so on.
We can write a general formula for the amount remaining:
A =A₀(½)ⁿ
where n is the number of half-lives
Data:
A₀ = 5 g
t = 30 min
Calculations:
(a) Convert the half-life to minutes
(b) Calculate n
(c) Calculate A
The answer is 0.62g.
Solution:
From year 1960 to year 2030, it has been
2030-1960 = 70 years
The half-life of the radioactive element is 28 years, then the sample will go through
70 years * (1 half-life/28 years) = 2.5 half-lives
Starting with a 3.5 gram sample, we will have
3.5*(1/2) after one half-life passes
3.5*(1/2) * (1/2) = 3.5*(1/4) after two half-lives pass
3.5*(1/4) * (1/2) = 3.5*(1/8) after three half-lives pass and so on
Therefore, we can write the remaining amount of the sample after the number n of half-lives have passed as
mass of sample = initial mass of sample/2^n
The mass of the remaining sample for n = 2.5half-lives can be now calculated as
mass of sample = 3.5 grams / 2^2.5 = 0.62 g
C, they could work together to make things from the top down.
