Identify the segment of the sentence which contains the grammatical error. If there is no error mark ‘No error’ as your answer.

When you press (A) the end call button (B) on the phone, (C) the call will disconnect automatically. (D) No Error (E)

The correct answer is Option 4 i.e., ‘the call will disconnect automatically’- the error lies in this part only.

• This is a conditional sentence, and in this type of sentence, one sentence depends upon the other because of cause and effect.
• The given sentence talks about a general fact that is always true- be it in the past, present, or future.
• This type of sentence uses the Zero Conditional where the conditional or subordinate clause begins with ‘if’ or ‘when’ and is followed by Simple Present Tense in both subordinate and main clauses and according to this rule, the error lies in Part D.

For example- When thunderstorms and lightning occur, little John gets frightened.

• In the given sentence, the verb ‘will disconnect’ in the Simple Future Tense is used instead of the Simple Present Tense ‘disconnects’ in the main clause.

Hence, ‘will disconnect’ should be replaced by ‘disconnects’.

So, the correct sentence is:

“When you press the end call button on the phone, the call disconnects automatically.” 

• Zero conditional is used when scientific facts are stated.

♦For example-

When the sun shines, dewdrops melts.

• Zero conditional is the only instance when the conditional word 'if' or 'when' can be interchanged and the meaning still remains intact.