Advertisements
Advertisements
प्रश्न
Consider a quantity of a radioactive substance. The fraction of this quantity that remains after t half-lives can be found by using the expression 3–t. After how many half-lives will the fraction be `1/243` of the original?
उत्तर
Given, t half-lives = 3–t
So, `1/243 = 3^-t`
⇒ `1/3^5 = 1/3^t` ...`[because 3 xx 3 xx 3 xx 3 xx 3 = 3^5 "and" a^-m = 1/a^m]`
On comparing both sides, we get t = 5 half-lives.
APPEARS IN
संबंधित प्रश्न
Express the given numbers in usual form.
1.0001 × 109
Write the following numbers in the usual form:
3.02 × 10−6
The standard form for 234000000 is ______.
Very large numbers can be expressed in standard form by using ______ exponents.
The standard form of `(1/100000000)` is ______.
Write 0.000005678 in the standard form.
The number of red blood cells per cubic millimetre of blood is approximately 5.5 million. If the average body contains 5 litres of blood, what is the total number of red cells in the body? Write the standard form. (1 litre = 1,00,000 mm3)
Express the following in standard form:
Mass of a molecule of hydrogen gas is about 0.00000000000000000000334 tons.
The paper clip below has the indicated length. What is the length in standard form.
The given table shows the crop production of a State in the year 2008 and 2009. Observe the table given below and answer the given questions.
| Crop | 2008 Harvest (Hectare) |
Increase/Decrease (Hectare) in 2009 |
| Bajra | 1.4 × 103 | – 100 |
| Jowar | 1.7 × 106 | – 440,000 |
| Rice | 3.7 × 103 | – 100 |
| Wheat | 5.1 × 105 | + 190,000 |
- For which crop(s) did the production decrease?
- Write the production of all the crops in 2009 in their standard form.
- Assuming the same decrease in rice production each year as in 2009, how many acres will be harvested in 2015? Write in standard form.
