Questions

This is a common error while compiling C program in Linux. This error occurs when you are using pthread_create function to create threads in your programs.

To fix this problem ensure following points:
Include header file pthread.h in your program.
Add –lpthread linker flag with compilation command.
1- Include Header file
#include <stdio.h>
#include <pthread.h>
...
...
2- Compile command
gcc main.c -o main -lpthread

Cuba

Mitochondria are known as 'Power House' of the cell because they produce energy in the form of ATP.

Satellites orbit the earth at a speed of 28,000 kmph.

Satellites that are further away actually travel slower. The International Space Station has a Low Earth Orbit, about 400 kilometers (250 miles) above the earth's surface. Objects orbiting at that altitude travel about 28,000 kilometers per hour (17,500 miles per hour).

Cambodia Capital- Phnom Penh, Currency- Cambodian riel.