Complete ionic:
Cu(aq) + 2Cl(aq) + 8O(aq) + 2Na(aq) + C(aq) + 3O(aq) = CaCO3(s) + 2Na(aq) + Cl(aq) + 4O(aq)
Net ionic:
Cu(aq) + Cl(aq) + 4O(aq) + 2Na(aq) + C(aq) + 3O(aq) = CaCO3(s)
So write everything out as IF it will dissociate in water. So everything that is aq splits but solid just floats to the bottom of the mixture. Cancel what you can (in this case the two from the ClO4 on the left of the equation cancels with the ClO4 from the right) and the 2Na cancels. Then, write out the whole solution and you are done!
Answer:
In an acid-base equilibrium, acid becomes a conjugate base and base becomes a conjugate acid.
Explanation:
Let's remember the Bronsted-Lowry theory to answer this specific question. According to the theory, acid is a proton donor, while a base is a proton acceptor.
Consider an acid in a form HA (aq) and base in a form of B (aq). Since acid is a proton donor, it will donate its hydrogen ion to the base, B. The resultant products would be
(aq) and
(aq).
Remember that an acid-base reaction is an equilibrium reaction. This means we may also look at this proton transfer reaction from the product side towards the reactants. Summarizing what has been said, we may write the equilibrium as:
⇄ 
Now acid, HA, donates a proton to become a conjugate base. The conjugate base, if we look from the reverse equation side, is actually a base, since it can accept a proton to become HA. Similarly, B accepts a proton to become a conjugate acid. Looking from the reverse reaction, it can now donate a proton, so in reality we can consider it a base.
To summarize, your logic is correct.
Answer:
In the option(A) moles of HCl left are 0.100 moles which is wrong, making the option incorrect.
Explanation:

Moles of HCl = n
Molarity of HCl = 1.0M
Volume of HCl solution = 30.0 mL = 0.030 L (1 mL = 0.001L)


Moles of Fe = 
According to recation , 1mol of Fe reacts with 2 mol HCl. Then 0.01 mole of Fe will recat with :
of HCl
This means that HCl uis in excess , hence excessive reagent.
Moles of HCl left unreacted :
= 0.030 mol - 0.020 mol = 0.010 mol
But in the option moles of HCl left are 0.100 moles which is wrong, making the option incorrect.
Smaller atoms and stronger bonds promotes greater hardness in minerals.
Answer:
The new acceleration becomes twice the pervious acceleration.
Explanation:
Given that,
Mass of the rock, m = 3 kg
Force, F = 1 N
We know that the force acting on an object is given by :
F = ma
a is acceleration of the rock
Put m = 3 kg and F = 1N,

If the force is doubled, F' = 2 N
So,
F'=ma'

So, the new acceleration becomes twice the initial acceleration.