Most of the Moon's basalts erupted between about 3 and 3.5 billion years ago, but the oldest samples are 4.2 billion years old, and the youngest flows, based on the age dating method of crater counting, are estimated to have erupted only 1.2 billion years ago.
        
             
        
        
        
Answer: The correct answer is B. He could add insulation to the aquarium so that it does not exchange energy with its surroundings.     
Explanation-
Isolated system is a system in which there is no exchange of energy and mass. As per the question, heat is radiated from the aquarium. In order to make it an isolated system, insulating or diathermic cover is used over it so that it does not exchange energy with its surroundings.     
 
        
                    
             
        
        
        
1. The general trend of human population growth is that the growth rate of population is increasing over the years
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2. Countries of the world differ in birth rates, death rates and age structure of population and this factor explains why population  in different countries grow at  different rates.
3. Demography is the study of human population in terms of births, deaths etc is called demography.
4. Demographic transition is the shift from high birth and death rates to high birth and low death rates and finally to low birth and death rates. Demographic transition reduces the rate of population growth of a country.
5. Age structure diagram contains data about individuals who belong to the younger age group. Once they become mature they will contribute to population growth and thus studying the age structure gives an idea the trends of future population growth.
 
        
             
        
        
        
well it is not exactly essentioal but salmon need it
 
        
             
        
        
        
Answer:
c. sexual dysfunction and dry mouth
Explanation:
Antidepressants are drugs prescribed by a medical professional in the treatment of patients that generally suffer from mood swings, depression, some acute pains, and to help deal with some addictions. 
Antidepressants are usually known to have sexual dysfunction, dry mouth, amongst others as side effects.
Some anti depressant drugs include Fluvoxamine, 
Paroxetine, and
Sertraline.