Ans. 
In humans, there are total of 46 chromosomes in each cell that show 23 pairs of chromosome. During reproduction, meiosis occurs in germ cells that leads to formation of daughter cells or gametes that contain half of the chromosomes as present in parent cells. Thus, each gamete (either male or female) contains 23 chromosome. 
During fertilization, fusion of male gamete or sperm(with 23 chromosomes) and female gamete or ovum(with 23 chromosomes) to form zygote that develops into multi-cellular offspring with 46 chromosomes.
Thus, 'a child inherit 46 chromosomes from his or her parent (23 chromosomes from each parent).'
 
        
                    
             
        
        
        
B. A question 
You need to think of a question to begin to make an experiment, otherwise how do you know what you’re trying to find?
        
                    
             
        
        
        
Living in herd is a structural adaptation.
There are three different kinds of adaptations: behavioural, physiological and structural.
Adaptations help animals survive and their ecosystem. 
The second sentence does not sound correct but it seems correct to me (just not in grammar).
Hope it helped!
        
                    
             
        
        
        
16 neutrons are present in the most abundant isotope.
Explanation:
Phosphorus has 18 isotopes. The most common isotope has mass number (no. of protons 15+ no. of neutrons 16=) 31 .
 
        
                    
             
        
        
        
Semen is the correct answer