Answer: (A) 
(B) 
Explanation:
(A) As we know that HCl is a strong acid and when it is added to an aqueous solution then it leads to increase in the concentration of hydrogen ions. And, when an acid or base is added to a solution then any resistance by the solution in changing the pH of the solution is known as a buffer.
This means that addition of buffer into the given solution will not cause much change in the concentration of 
in large amount.
As both the buffer components are salt then they will remain dissociated as follows.
Hence, net ionic equation will be as follows.
(B) When we add small amount of sodium hydroxide into the solution then there will occur an increase in concentration of hydroxide ions into the solution. But then due to the presence of buffer there will occur not much change in concentration and the acid will get converted into salt.
The net ionic equation is as follows.
Answer: The mass of aluminium sample is 55.4 gram
Explanation:
As we know that,
![m_1\times c\times (T_{final}-T_1)=-[m_2\times c\times (T_{final}-T_2)]](https://tex.z-dn.net/?f=m_1%5Ctimes%20c%5Ctimes%20%28T_%7Bfinal%7D-T_1%29%3D-%5Bm_2%5Ctimes%20c%5Ctimes%20%28T_%7Bfinal%7D-T_2%29%5D)
where,
= mass of aluminium = ?
= mass of water = 300.0 g
= final temperature = 
= temperature of aluminium = 
= temperature of water = 
= specific heat of aluminium = 
= specific heat of water = 
Now put all the given values in equation (1), we get
![-[m_1\times c_1\times (T_{final}-T_1)]=[m_2\times c_2\times (T_{final}-T_2)]](https://tex.z-dn.net/?f=-%5Bm_1%5Ctimes%20c_1%5Ctimes%20%28T_%7Bfinal%7D-T_1%29%5D%3D%5Bm_2%5Ctimes%20c_2%5Ctimes%20%28T_%7Bfinal%7D-T_2%29%5D)
![-[m_1\times 0.897\times (23.8-94.5)^0C]=[300.0g\times 4.184\times (23.8-21.0)]](https://tex.z-dn.net/?f=-%5Bm_1%5Ctimes%200.897%5Ctimes%20%2823.8-94.5%29%5E0C%5D%3D%5B300.0g%5Ctimes%204.184%5Ctimes%20%2823.8-21.0%29%5D)
Therefore, the mass of aluminium sample is 55.4 gram
Explanation:
1.
Given parameters:
Frequency of the radiation = 8.4 x 10¹⁴Hz
Unknown:
Energy of the wave = ?
Solution:
The energy of a wave is given by the expression below;
E = hf
E is the energy
h is the Planck's constant = 6.63 x 10⁻³⁴m²kg/s
f is the frequency
Now insert the parameters and solve;
E = 6.63 x 10⁻³⁴m²kg/s x 8.4 x 10¹⁴Hz
E = 5.57 x 10¹ x 10⁻²⁰J
E = 5.57 x 10⁻¹⁹J
2.
Given parameters:
Wavelength = 2.13 x 10⁻¹³m
Unknown:
Frequency of the wave = ?
Solution:
The frequency of a wave can be determined using the expression;
C = f∧
C is the speed of light = 3 x 10⁸m/s
f is the frequency
∧ is the wavelength
f = 
= 
= 1.41 x 10²¹hz
Answer:Two more hydrogen atoms will be required
Explanation:
A carbon atom has 4 valence electrons in its outermost shell,thus it can form 4 covalent bonds.Two pairs of electrons are shared in a double bond between C-C atom.two more electrons are left which is shared with two hydrogen atoms.
Colligative properties depend on the amount of solute dissolved in a solvent. These set of properties do not depend on the type of species present. These properties include freezing point depression, boiling point elevation, osmotic pressure and vapor pressure lowering.
