Answer:
K I will attempt
Explanation:
a)
b)
1 : 2 : 2 (I don't know if this is what the question wants but it is what I would answer)
c)
Hydrogen because it requires 2 moles of H2 to react with 1 mole of O2
d)
24 moles of water. Look at stoichiometric coefficient. 2:2 means 24 moles you get 24 moles
e)
Oxygen. 2 < 5/2. Remember, 1 mole of O2 requires 2 moles of H2. But 5/2 is still greater than 2
f)
First, let's find out how many moles of water we can get. Since O2 is the limiting reactant, and O2:H2O ratio is 1:2, we will get 4 moles of H2O. Then, we can multiply 4 by Avogadro's number which is 
to get the number of molecules. We get: 2.41 * 10^24 molecules of water.
Answer:
Total 5 significant digits.
Explanation:
Significant digits are the numbers that give a meaningful contribution. For example, digit 013 has the 2 significant digits and zero is not a significant digit because digits 1 and 3 give meaningful contribution but digit zero does not value meaningful contribution. Similarly, the 89015 has a total of 5 significant digits and these digits are the 8, 9, 0, 1, and 5.
Answer:
320 g
Step-by-step explanation:
The half-life of Co-63 (5.3 yr) is the time it takes for half of it to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Mass
half-lives t/yr Remaining Remaining/g
0 0 1
1 5.3 ½
2 10.6 ¼
3 15.9 ⅛ 40.0
4 21.2 ¹/₁₆
We see that 40.0 g remain after three half-lives.
This is one-eighth of the original mass.
The mass of the original sample was 8 × 40 g = 320 g
B, Rocks are always being recycled into different forms.
Answer:
Group 7 or the Halogens
Explanation:
The halogens occupies the 7th group on the periodic table. The group is made of F, Cl , Br, I and At.
The elements in this group are the most reactive of all elements. They are very reactive because they have just 7 electrons in their outermost shell and they only require an electron to complete their electronic configuration to produce an octet which typically mimics the stable group VIII elements.
This makes them very highly reactive.
