Answer:
The correct answer is- Normal vaginal pH is acidic (4 to 5), which protects from infection.
Explanation:
The vaginal part in woman have high tendency to get infection because of moist internal condition and its location but vagina also have a protective mechanism which protect it from the infection.
A woman's vagina contains many species of Lactobacillus genus which secrete lactic acid and hydrogen peroxide that maintains the low pH level in the vagina. So due to this reason, the normal pH of the vagina remains between 4-5 which does not allow pathogenic bacteria to flourish and cause infection.
 
        
             
        
        
        
Answer:
More than 7000 chemicals are present in tobacco smoke. 
Explanation: 
In these 7000 chemicals, 250 are harmful to the human body such as carbonmonoxide, ammonia and hydrogen cyanide etc. There are some chemicals that are found in tobacco smoke which causes cancer disease in human. About 69 chemicals out of 250 are present in tobacco smoke that causes cancer disease. So its consumption is dangerous for health. 
 
        
                    
             
        
        
        
Answer:
Viruses mutate very quickly The major reason that viruses evolve faster than say, mosquitoes or snakes or bed bugs, is because they multiply faster than other organisms. And that means every new individual is an opportunity for new mutations as they make a copy of their genetic material. Many of those mutations have no noticeable effect.
Explanation: