The half-life of Plutonium−239, t1/2 is 2.41 × 10⁴<span> yrs
time taken to reach tolerable level = seven half-lives
= 7 x t1/2
= 7 x </span>2.41 × 10⁴ yrs
= 168700 yrs
= 1.687 x 10⁵ yrs
Hence, the period of time that <span>Plutonium-239 must be stored is </span>1.687 x 10⁵ years.
Answer:
The correct answer is number 2. Elliptical, Spiral, Irregular.
Explanation:
Unfortunately, you did not attach the passage. Without the passage, we do not know what its content is.
So we are going to answer this question with our own knowledge.
The types of galaxies by their ability to form new stars, from most to least activity are "Elliptical, Spiral, Irregular."
That is the way astronomers classify galaxies in scientific terms. These scientists consider that the smallest galaxies or dwarf galaxies have approximately 100 million stars. On the other hand, giant galaxies have billions or trillions of stars. That immense is our universe.
Scientists still studying the universe and the galaxies to understand the way galaxies are formed.
The answer is C, it makes the block easier to lift by changing the direction of the force needed to lift it
These gases very rarely react, with others and also noble gases are odourless and colourless.
Explanation:
- Noble gases will not react with anything so that is the reason why they are known as an inert gas.
- Noble gases are present in group 18 on the periodic table and following the rule of the octet which is they completed their orbital by s2p6 which is the highest energy level.
- Most elements are discovering through their reactivity with the other elements, commonly with oxygen. In the case of a noble gas, it is difficult for a scientist to work with the gases which have very less or no chemical property in terms of their reactivity.
