Corpus luteum in pregnancy has a long life. However, if fertilization does not take place, it remains active only for 10-12 days. Explain.

What is implantation? Where does it take place? How many days after fertilization does it take place in humans? Explain breifly how it occrs.

Synthetic polymers are finding applications in almost all spheres of life and are making our life comfortable. Their large scale use has been based on their relative inertness to environment Process giving them durability for long time. However, their long durability is not altogether an advantage. These solid wastes remain undegraded for quite a long time and their disposal has created a serious problem of waste management. If the overuse of plastics continues, it will pose a serious threat to all of us. After reading the above passage, answer the following question : Is it advisable to continue with overuse of plastics due to their immense use in our daily life?

A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to- 3.125%

Distinguish between isotopes and isobars. Give one example for each of the species. A radioactive isotope has half life of 5 years. How long will it take the activity to reduce to 3.125%.

One day in the morning, Ramesh filled up 1/3 bucket of hot water from geyser, to take bath. Remaining 2.3 was to be filled by cold water (at room temperature) to bring mixture to a comfortable temperature. Suddenly Ramesh had to attend to something which would take some time say 5 - 10 minutes before he could take bath. Now the he had two options: (i) fill the remaining bucket completely by cold water and then attend to the work, (ii) first attend to the work and fill the remaining bucket just before taking bath. Which option do you think would have kept water warmer ? Explain.

A radioactive isotope has a half-life of T years. How long will it take the activity to reduce to - 1% of its original value?

A cobalt-60 source having a half-life of 5.27 years is calibrated and found to have an activity of 3.50 xx 10^5 Bq.The uncertainty in the calibration is +- 2% .Calculate the length of time.in days, after the calibration has been made, for the stated activity of 3.50 xx 10^5 Bq to have a maximum possible error of 10%.

We would like to prepare a scale whose length does not change with temperature. It is proposed to prepare a unit scale of this type whose length remains, say 10 cm. We can use a bimetallic strip made of brass and iron each of different length whose length (both components) would change in such a way that difference between their lengths remains constant. If alpa_(iron = 1.2 xx 10^-5 //K and alpha_(brass = 1.8 xx 10^-5//K , what should we take as length of each strip?

Radioactive disintegration is a first order reaction and its rate depends only upon the nature of nucleus and does not depend upon external factors like temperature and pressure. The rate of radioactive disintegration (Activity) is represented as -(dN)/(dt)=lambdaN Where lambda= decay constant, N= number of nuclei at time t, N_(0) =initial no. of nuclei. The above equation after integration can be represented as lambda=(2.303)/(t)log((N_(0))/(N)) Half-life period of U is 2.5xx10^(5) years. In how much time will the amount of U^(237) remaining be only 25% of the original amount ? a) 2.5xx10^(5) year b) 1.25xx10^(5) years c) 5xx10^(5) years d) none of these