What is the primary difference between a CD and a DVD? MCQ with Answer and Explanation

What is the primary difference between a CD and a DVD?
A. CDs are read-only; DVDs are rewritable
B. DVDs use a shorter wavelength laser, allowing higher density
C. DVDs are older technology
D. CDs store more data than DVDs
Answer: Option B
Solution (By JKSSB Mock Tests)
DVDs use a shorter wavelength laser (650 nm vs 780 nm for CDs), which allows smaller pits and tighter tracks, resulting in higher storage capacity (4.7 GB vs 700 MB).

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Practice More Memory and Storage Devices Questions

Question #1
What is the capacity of a standard CD-ROM?
A. 650-700 MB
B. 4.7 GB
C. 120 MB
D. 25 GB

Correct Answer: Option A


Explanation:
A standard CD-ROM holds about 650 to 700 MB of data (or 74-80 minutes of audio). DVD holds 4.7 GB, and Blu-ray 25 GB.

This question belongs to: Computer Memory and Storage Devices
Question #2
What storage unit is equivalent to $1024^{6}$ bytes ($2^{60}$ bytes) in computer data storage scaling scales?
A. 1 Exabyte
B. 1 Zettabyte
C. 1 Yottabyte
D. 1 Petabyte

Correct Answer: Option A


Explanation:
The scaling path for binary exponents places $2^{10}$ as KB, $2^{20}$ as MB, $2^{30}$ as GB, $2^{40}$ as TB, $2^{50}$ as PB, and $2^{60}$ bytes as 1 Exabyte (EB).

This question belongs to: Computer Memory and Storage Devices
Question #3
How many bits are contained within a data block size of exactly 4 Bytes?
A. 16 bits
B. 32 bits
C. 64 bits
D. 128 bits

Correct Answer: Option B


Explanation:
Since one byte is strictly defined as 8 bits, a 4-byte block contains exactly $4 imes 8 = 32$ bits.

This question belongs to: Computer Memory and Storage Devices