CH3CN acts as an electrophile due to the positive charge on the carbon atom which is due to the electronegativity difference between C and N atoms. It is also a weak nucleophile due to the presence of lone pair of electrons on N atom. But as it is sp hybridised so it act as a weak necleophile.These are attacked only by strong electrophiles usually cations.
CH3Cl is an electrophile whereas CH3OH and CH3NH2 are nucleophiles.

Explanation:

In order to determine which compound acts as both a nucleophile and an electrophile, we need to understand the properties of nucleophiles and electrophiles.

Nucleophile:
A nucleophile is a species that donates a pair of electrons to form a new covalent bond. Nucleophiles are typically negatively charged or have a lone pair of electrons available for bonding.

Electrophile:
An electrophile is a species that accepts a pair of electrons to form a new covalent bond. Electrophiles are typically positively charged or have an electron-deficient center.

Now, let's analyze each compound and determine if it acts as a nucleophile or an electrophile.

a) CHCl:
CHCl does not possess any lone pair of electrons or a negative charge. It cannot donate a pair of electrons, so it cannot act as a nucleophile. It also does not have a positive charge or an electron-deficient center, so it cannot act as an electrophile.

b) CHCN:
CHCN has a lone pair of electrons on the nitrogen atom. It can donate this lone pair of electrons to form a new covalent bond, making it a nucleophile. Additionally, the carbon atom in CHCN has a partial positive charge due to the electronegativity difference between carbon and nitrogen. This electron-deficient carbon can accept a pair of electrons, making CHCN an electrophile.

c) CHOH:
CHOH contains an oxygen atom with two lone pairs of electrons. It can donate these lone pairs of electrons, making it a nucleophile. However, the carbon atom in CHOH does not have a positive charge or an electron-deficient center, so it cannot act as an electrophile.

d) CHNH:
CHNH does not possess any lone pair of electrons or a negative charge. It cannot donate a pair of electrons, so it cannot act as a nucleophile. The nitrogen atom in CHNH has a partial positive charge due to the electronegativity difference between carbon and nitrogen. This electron-deficient nitrogen can accept a pair of electrons, making CHNH an electrophile.

Conclusion:
Out of the given compounds, CHCN acts as both a nucleophile and an electrophile. It has a lone pair of electrons on nitrogen, allowing it to act as a nucleophile, and the carbon atom has a partial positive charge, allowing it to act as an electrophile.