<h3>Answer:</h3>
18.75 grams
<h3>Explanation:</h3>
- Half-life refers to the time taken by a radioactive material to decay by half of the original mass.
- In this case, the half-life of element X is 10 years, which means it takes 10 years for a given mass of the element to decay by half of its original mass.
- To calculate the amount that remained after decay we use;
Remaining mass = Original mass × (1/2)^n, where n is the number of half-lives
Number of half-lives = Time for the decay ÷ Half-life
= 40 years ÷ 10 years
= 4
Therefore;
Remaining mass = 300 g × (1/2)⁴
= 300 g × 1/16
= 18.75 g
Hence, a mass of 300 g of an element X decays to 18.75 g after 40 years.
Answer:
copper
Explanation:
so for this you can work out the mass for both and compare
so mass = moles × mr
so mass of sodium = 1 × 23= 23 g
and mass of copper = 1 × 63.5= 63.5 g
so copper have more mass :)
Salt hydrates are an important class of PCMs. An inorganic salt hydrate (hydrated salt or hydrate) is an ionic compound in which the ions attract a number of water molecules, which are then trapped inside the crystal lattice. A hydrated salt has the generic formula MxNy. nH2O.
Answer:
Explanation:
final temperature of the cube
initial temperature of the cube
mass of the cube
specific heat of aluminum
The average atomic mass if the element above is calculated by the sum of the product of the isotope abundance and its atomic mass unit. It is expressed as:
Average atomic mass = Σ xi(Mi)
<span>Average atomic mass = (.7547 x 248.7) + (.2453 x 249.4) = 248.87
</span>
Hope this helps.
