d. br
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bromine of the following elements is classified as a halogen
Answer:
Explanation:
scheelite is CaWO₄
Mol weight = 288
80 g of scheelite = 80 / 288 = 27.77 x 10⁻² moles
27.77 x 10⁻² moles of scheelite = 27.77 x 10⁻² x 6.02 x 10²³ molecules of scheelite
= 167.17 x 10²¹ molecules of scheelite
1 molecule of scheelite contains 4 atoms of oxygen
167.77 x 10²¹ molecules of scheelite contains 4 x 167.77 x 10²¹ atoms of oxygen .
= 671.08 x 10²¹ atoms of oxygen .
= 671 x 10²¹ atoms .
The density of any substance does not change at a certain temperature and pressure. Even though mass and volume are intensive properties (depends on the amount of substance), density is not. It is merely a fixed ratio of mass to volume. Therefore, the solution is
Density = Mass/Volume
For your information, quantitatively, cm³ is equivalent to mL.
Density = 100 g/4.67 cm³ = 21.41 g/cm³
<u>Answer: </u>The volume occupied by 
at STP is 0.56 L.
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
We are given:
Given mass of oxygen = 0.80 g
Molar mass of oxygen = 32 g/mol
Putting values in above equation, we get:
<u>At STP:</u>
1 mole of a gas occupies 22.4 L of volume.
So, 0.025 moles of oxygen gas will occupy = 
of volume.
Hence, the volume occupied by at STP is 0.56 L.
Answer:
Three half lives corresponds to (12)3 . So a 18 quantity of the original isotope is retained. And the percentage of quantity of a radioactive material that remains after 5 half-lives will be . ∴NN0×100=10032=3.125.
