Answer:
The correct answer is - 800.
Explanation:
Given:
Total amount = ? or assume x
spend in buying birthday item = 3/4 of x
given to sister = 1/5 of x
remaining to mother = 40
solution:
the remaning amount = x- (3x/4+x/5) = 4=
=> x- 19x/20 = 40
=> x = 20*40
=> x = 800
thus, the correct answer is = 800
Answer:
(A) endothermic
(A) Yes, absorbed
Explanation:
Let's consider the following thermochemical equation.
2 Fe₂O₃(s) ⇒ 4 FeO(s) + O₂(g) ΔH = 560 kJ
Since ΔH > 0, the reaction is endothermic.
We can establish the following relations:
- 560 kJ are absorbed when 2 moles of Fe₂O₃ react.
- The molar mass of Fe₂O₃ is 160 g/mol.
Suppose 66.6 g of Fe₂O₃ react. The heat absorbed is:

Answer:
MgCl₂+ Na₂CO₃ ==> MgCO₃ + NaCl
From a quick observation
You see that the right hand side of the eqn is deficient of Sodium and Chlorine
Simply Add a Coefficient of 2 to NaCl to balance it with the left.
Your answer now becomes
MgCl₂ + Na₂CO₃ ==> MgCO₃ + 2NaCl.✅
#1. An element or ion that has lost two electrons must have a net charge of 2+, because it has two more protons than electrons, therefore the answer is Mg2+
#2. aluminum ions have an oxidation state of 3+ and fluoride has an oxidation state of 1-, therefore I’m order for the charges to cancel you need 3 fluoride ions.
Therefore, the answer is AlF3