(15)

The decomposition of a compound P at temperature T according to the equation

is a first order reaction. After 30 minutes from the start of the decomposition in a closed vessel, the total pressure developed is found to be 317 mm Hg and after a long period of time the total pressure is observed to be 617 mm Hg. Calculate the total pressure of the vessel after 75 minutes. Given: Vapour pressure of S(l) at temperature T = 32.5 mm Hg.

Submission: Closed

Ans: 379.73mm Hg

Cracked by:

  1. Tushar Jain, Meerut Public School, Meerut U.P.
  2. Yash Agrawal, Bhopal (M.P.).
  3. Anupam Narayan, Class XII, Swami Vivekanand Junior College, Mumbai.
  4. Umang Merwana, Satna (M.P.).
  5. Jithin Prakash, 12, Army School, Deolali

(14)

On the surface of the earth at 1 atm. pressure, a balloon filled with hydrogen gas occupies 500ml. This volume is 5/6 of its maximum capacity. The balloon is left in the air. It starts rising. Calculate the height (in metres) above which the balloon will burst if temperature of the atmosphere remains constant and pressure decreases 1mm Hg for every 1 metre rise of height.

Submission: Closed

Ans: 126.67metre

Cracked by:

  1. Mandeep Bamal, Inter University Microelectronics Center (IMEC), Leuven, BELGIUM
  2. Poonam Kaur Adarsh, Pune (Maharashtra)
  3. Rajat Shrivastava, Bhopal (M.P.), Rajat has scored 98% marks in X'th board Maths subject, congrats!
  4. Nishant Kumar, Class XII, Modern School, Nagpur (Maharashtra).
  5. Jathin Das, Class XII, A.D.I.S., Abu Dhabi.

(13)

Evaluate

Submission: Closed

Ans: -2

Cracked by:

  1. Yash Agrawal, Bhopal (M.P.).
  2. Nishant Kumar, Class XII, Modern School, Nagpur (Maharashtra).
  3. Tushar Jain, Meerut U.P.
  4. Satish Kumar, National Public School Rajajinagar, Bangalore.
  5. Gaurav Mathur, XII'th, Maheshwari Sr. Secondary School, Jodhpur.

(12)

What is the resistance experienced by the current in the mesh. Each lead of the small square has a resistance R.

Submission: Closed

Nachiket's Solution (.pdf)

Cracked by:

  1. Yash Agrawal, Bhopal (M.P.).
  2. Nachiket Vasant Vaidya, 12'th, Sathaye College, Vile Parle, Mumbai.

(11)

Find the resistance of the network between the points A & B as shown in the figure. The resistance of each resistor is R.

Submission: Closed

Ans: 7R/15

Last modified: Monday, 28 November 2011, 2:13 PM