Questions

‘has’ is incorrectly used since the sentence is in past tense. Moreover, the subject is cities, which is plural.

The Earth has four major systems or spheres. These systems are

 1. The geosphere,

 2. The hydrosphere,

 3. The atmosphere, and 

4. The biosphere.

The biosphere is the system where we belong.

Market failure arises because it is not possible for the market to correctly weight cost and benefits in a situation in which some of the cost is completely unaccounted.

Demand-side market failures happen when demand curves do not reflect consumer’s full willingness to pay for goods or services.

Supply-side market failures occur when supply curves do not reflect the full cost of producing a good or services.

#include<stdio.h>
int main(){
    int a=5,b=10;
    a=b+a;
    b=a-b;
    a=a-b;
    printf("a= %d  b=  %d",a,b);
}

The current Chairman of Indian Space Research Organisation(ISRO) is Kailasavadivoo Sivan.

The ozone gas present in the atmosphere absorb ultraviolet radiation. It is spread as a ozone layer throughout the stratosphere.