Hi Ratnaa19,
On the GMAT, you can expect a total of four Reading Comprehension passages divided into long passages (containing 4 questions) and short passages (containing 3 questions). However, you won’t always get the same number of long and short passages (you could see 2 long and 2 short or 1 long and 3 short).
Regarding timing, you should spend roughly 2 to 3 minutes reading the short passages and 3 to 4 minutes reading the long ones. Since you should have a rough idea of what you read after reading the passage, each question should take you roughly 30 seconds to 1.5 minutes and to answer. Thus, look to spend a total of about 6 to 8 minutes on each RC section.