Answer: 2s and 2p
Explanation: Carbon is an element with atomic number of 6 and thus contains 6 electrons. The electrons are filled in order of increasing energies and follows Afbau's rule.The electrons are singly filled first in each orbital having same spin, then only pairing occurs. This rule was known as Hund's Rule.
The valence electrons are the electrons which are present in last shell. Thus valence electrons are 4, two in s and 2 in p orbitals.
Mass of potassium hydrogen pthalate KHP is 0.4856 g, its molar mass is 204.22 g/mol, number of moles of KHP can be calculated as follows:
Here, m is mass and M is molar mass, putting the values,
This will be number of moles of NaOH at equivalent point.
Detailed calculations:
Molarity is defined as number of moles in 1 L of solution, for 250 mL of solution, molarity will be:
For 25 mL, apply dilution law as follows:
Putting the values,
On rearranging,
Convert molarity into number of moles,
At equivalent point, number of moles of KHP will be equal to NaOH, thus, number of moles of NaOH will be 0.00237 mol.
Calculation for molarity:
Volume of NaOH is 18.75 mL, thus, molarity can be calculated as follows:
Putting the values,
Therefore, molarity of NaOH is 0.1264 M