SSC CGL 2025 Tier-II · Paper-I, 19 January 2026 · Computer Knowledge Test · Question 13 of 150

We transcribed this text from the pictures of a candidate's response sheet for this paper; the answer is the key SSC marked with a green tick on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. This paper reaches us as a candidate's response sheet saved as pictures, so we transcribed the text from those pictures, and a second reader checked every question against them; where the layout carries meaning, we show the picture too. Each answer is the key SSC marked with a green tick on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. UnlockIAS wrote the solutions.

What is the main purpose of using a file compression technique before uploading to cloud storage?

(a)To convert the file into a secure format
(b)To reduce the file size and save storage space
(c)To encrypt the file
(d)To make the file readable across different devices

Answer

Why

Correct — B. Compression re-encodes a file so that it takes fewer bytes, by removing redundancy in the data. Lossless formats, such as the DEFLATE format gzip uses, rebuild the original exactly.

A smaller file uses less cloud storage and less data to upload → option (b).

Why the others are wrong

(a)
To convert the file into a secure format — Compression protects nothing, so it does not make a secure format: anyone with a standard decompressor gets the original back. Security needs encryption or access control.
(c)
To encrypt the file — Encryption scrambles data so that only a key holder can read it. Compression only shrinks it, and a compressed file opens for anyone with the matching decompressor.
(d)
To make the file readable across different devices — Compression adds a step: the file must be decompressed before use, and it then still needs software that reads its original format. It does not make a file readable on more devices.

Concept

Data compression stores the same information in fewer bits. RFC 1951, which defines DEFLATE, puts it plainly: any compression method involves the reduction of redundancy in the data.

Lossless compression, used for documents and archives, returns the exact original. Lossy compression, such as JPEG for photos, discards some detail to get a smaller file.

Compressing before an upload shrinks the storage used and the data sent. It changes nothing about who can read the file.

Key facts

Compression reduces redundancy in data so that it needs fewer bytes (RFC 1951).
Lossless compression, such as DEFLATE, rebuilds the original data exactly.
Compression is not encryption: any matching decompressor restores the content.

Study next

Lossless against lossy compression, with ZIP and JPEG as examplesEncryption at rest and in transit for cloud storageCommon archive formats: ZIP, gzip, RAR

Common traps

Treating a zipped file as protected, when compression hides nothing.
Picking 'secure format' because a compressed file looks unreadable in a text editor.

Two wrong options borrow security words, 'secure format' and 'encrypt', that belong to encryption. Encryption itself is tested at 19 Jan 2026, 11:00 AM, Computer Knowledge Q.15 and at 19 Jan 2026, 11:00 AM, Computer Knowledge Q.20.

Related PYQs

No directly related past PYQ was found.