These questions make some students VERY nervous!

March 17, 2009
Our in-house team of subject experts, answers queries and clarify doubts posted by Topper readers like YOU. Read on to get a sneak peak of what makes Class XI students REALLY nervous!

SUBJECT: Mathematics

Q. Find the principle and general solution of secx = 2.

Posted by: Dev15

A. Given that, secx = 2
=> cos x = 1/2
cos x = cos π/3

Using formula for general solution of cos x = cos y ie, x = 2n π ± y,
We have x = 2n π ±π/ 3 as the general solution.

The solutions that lie in the interval [0, 2 π] are principal solutions.
So the solutions in this case are π/3 and 5π/ 3.
SUBJECT : Chemistry

Q. What is the ionization enthalpy of the hydrogen atom?

Posted by: Akshita

A. The ionization enthalpy (energy) of an element is defined as the energy required to remove an electron from a gas phase atom of an element. The ionization enthalpy of hydrogen atom is 13.6 eV.

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