Answer:
Index fossil, any animal or plant preserved in the rock record of the Earth that is characteristic of a particular span of geologic time or environment.
Explanation:
True
<u>Answer:</u> The isotopic symbol of barium is
and that of strontium is 
<u>Explanation:</u>
Nuclear fission reactions are defined as the reactions in which a heavier nuclei breaks down in two or more smaller nuclei.
In a nuclear reaction, the total mass and total atomic number remains the same.
- For the given fission reaction:

Total mass on reactant side = total mass on product side
235 + 1 = A + 94 + 3
A = 139
Total atomic number on reactant side = total atomic number on product side
92 + 0 = Z + 36 + 0
Z = 56
The isotopic symbol of barium is 
- For the given fission reaction:

Total mass on reactant side = total mass on product side
235 + 1 = A + 143 + 3
A = 90
Total atomic number on reactant side = total atomic number on product side
92 + 0 = Z + 54 + 0
Z = 38
The isotopic symbol of strontium is 
Hence, the isotopic symbol of barium is
and that of strontium is 
There are 4 significant figures! Start counting after the first non-zero digit :)
Hope this helps.
Answer:
1.8 moles of NaCl must be produced.
Explanation:
Based on the reaction:
HCl + NaOH → NaCl + H2O
<em>1 mol of HCl reacts with 1 mol of NaOH to produce 1mol of NaCl</em>
<em />
To solve this question we must find, as first, the <em>limiting reactant:</em>
<em />
1.8 moles of HCl will need 1.8 moles of NaOH for a complete reaction (Ratio of reaction 1:1). As there are 3.3 moles of NaOH,
<em>HCl is limiting reactant</em>
<em />
When the 1.8 moles of HCl react completely,
1.8 moles of NaCl must be produced because 1 mole of HCl produce 1 mole of NaCl
<span>If I done the math correctly it is 3729J because you multiply 16.5 g by the 2260 J/g and get 3729 J</span>