Sample of carbon obtained from any living organism has a decay rate of 15.3 decays per gram per minute. A sample of carbon obtained from very old charcoal shows a disintegration rate of`12.3` disintegrations per gram per minute. Determine the age of the old sample given the decay constant of carbon to be `3.839 xx 10^-12 per second `

Before the year 1900 the activity per unit mass of atmospheric carbon due to the presence of 14 C averaged about 0.255Bq per gram of carbon. An archaeological specimen containing 500 mg of carbon, shows 174 decays in one hour. What is the age of the specimen, assuming that its activity per unit mass of carbon when the specimen died was equal to the average value of the air?Half life of ^ 14 C is 5730years?

The rate constant of a first order reaction is 3 xx 10^(-6) per second. If the initial concentration is 0.10 M , the initial rate of reaction is

Disintegration rate of a sample is 10^10 per hour at 20 hrs from the start. It reduces to 6.3 xx 10^9 per hour after 30 hours. Calculate its half life andthe initial number ofradioactive atoms in the sample.

A ladder 20 ft long leans against a vertical wall. The top end slides downwards at the rate of 2 ft per second. The rate at which the lower end moves on a horizontal floor when it is 12 ft from the wall is a) 8/3 b) 6/5 c) 3/2 d) 17/4

Read the following passage write the appropriate amount in the boxes and discuss. Govind, who is a dry land farmer from Shiralas has a 5 acre land. His family inclde his wife two children and his old mother. He borrowed one lakh twenty five thousand rupees from the bank for one year as agriculatral loan at 10 p.c.p.a . He cultivated soyabean in x acres and cotton and tur in y acres. He spent Rs. 10,000 on seeds. The expenses for fertilizers and pesticides for the soyabean crop was 2000x rupees and 4000x2 rupees were spent on wages and cultivation of land. He spent 8000 y rupees on fertilizers and pesticides and rupees 9000 y2 for wages and cultivation of land for the cotton and tur crops. Let us write the total expenditure on all the crops by using variables x and y. rupees. He harvested 5x2 quintals soyabean and sold it at Rs. 2800 per quintal. The cotton crop yield was 5/3y2 quintals which fetched Rs. 5000 per quintal. The tur crop yield was 4y quintals and was sold at Rs. 4000 per quintal. Let us write the total income in rupees that was obtained by selling the entire farm produce, with the help of an expression using variables x and y. square + square + square rupees