Answer:
0.693 (you can round it up if you want to)
Explanation:
Density= mass ÷ volume
54.2 ÷ 78.1 = 0.693
I hope this helped☺
Answer:
c. contraction
Explanation:
Heating will cause substances to expand, or change their state (like solid to liquid) or it may be a chemical reaction.
<span><span>Yes.
An element that is highly electronegative pulls more on the electrons
in a bond, such as oxygen in H20. This creates a polar bond, where
there is a small negative charge on the oxygen, and a small positive
charge in between the hydrogens.
</span>Credit goes to "Erin M" answered on yahoo answers a decade ago.
</span>
Answer: (E) 300 bq
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is represented by 
Half life of Thallium-208 = 3.053 min
Thus after 9 minutes , three half lives will be passed, after ist half life, the activity would be reduced to half of original i.e.
, after second half life, the activity would be reduced to half of 1200 i.e.
, and after third half life, the activity would be reduced to half of 600 i.e.
,
Thus the activity 9 minutes later is 300 bq.
Answer: There are
atoms in 24 moles of Fe.
Explanation:
According to the mole concept, 1 mole of a substance contains
atoms.
Therefore, atoms present in 24 moles of Fe are calculated as follows.

Thus, we can conclude that there are
atoms in 24 moles of Fe.