Answer:
Average atomic mass = 15.86 amu.
Explanation:
Given data:
Number of atoms of Z-16.000 amu = 205
Number of atoms of Z-14.000 amu = 15
Average atomic mass = ?
Solution:
Total number of atoms = 205 + 15 = 220
Percentage of Z-16.000 = 205/220 ×100 = 93.18%
Percentage of Z-14.000 = 15/220 ×100 = 6.82 %
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) / 100
Average atomic mass = (93.18×16.000)+(6.82×14.000) /100
Average atomic mass = 1490.88 + 95.48 / 100
Average atomic mass = 1586.36 / 100
Average atomic mass = 15.86 amu.
Answer:
Reaction A, B, E and F are exothermic reactions.
Explanation:
Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system.
The total enthalpy of the reaction 
comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system.
The total enthalpy of the reaction comes out to be positive.
So, from the given option reaction which are exothermic are with negative value that enthalpy of reaction and those are:
1) 
,ΔH = -1203 kJ/mol
2)
,ΔH =-176 kJ/mol
3) 
,ΔH = -393.5 kJ/mol
4) 
,ΔH =-891 kJ/mol
An endothermic reaction needs energy to proceed, such energy is usually taken from the environment surrounding the reaction. In the typical case this energy is expressed as heat. Heat is an state of atomic activity, that energy is transferred to an ENDOthermic reaction so the initial threshold of reaction is overcome and the final reaction can occur.
Answer:
B. Warm and wet
Explanation:
higher temperatures and more rainfall increase chemical weathering, rocks in tropical regions weather more than in other regions.
(a) 43.6 mg; (b) 520 mg
(a) <em>Mass of phosphoric acid (PA) in a dose
</em>
Mass of PA = 2 tsp × (21.8 mg PA/1 tsp) = 43.6 mg PA
(b) <em>Mass of PA in the bottle
</em>
<em>Step 1</em>. Convert <em>ounces to millilitres
</em>
Volume = 4 oz × (30 mL/1 oz) = 120 mL
<em>Step 2.</em> Calculate the mass of PA
Mass of PA = 120 mL × (21.8 mg PA/5 mL) ≈ 520 mg PA
