Memory Units — Set 2

Correct Answer: D. 2

• **2 Nibbles = 1 Byte** because each nibble holds 4 bits, and a standard byte holds 8 bits — so splitting a byte down the middle gives exactly two nibbles. • **This pairing allows one byte to represent two hexadecimal digits** — the upper nibble stores the first hex digit and the lower nibble stores the second, which is why bytes are often written as two-digit hex values like 0xFF. • In color encoding, each color channel (Red, Green, Blue) is stored in one byte (00–FF), making nibble-awareness essential for graphics programming. • 💡 Option A (1) is wrong because one nibble is only 4 bits, not 8; Option B (8) is wrong because 8 nibbles would equal 32 bits, which is 4 bytes; Option C (4) is wrong because 4 nibbles would equal 16 bits, which is 2 bytes.

Correct Answer: A. Exabyte

• **Exabyte (EB) = 1024 Petabytes**, making it the unit used to measure internet-scale data flows, large government databases, and global data center archives. • **The world generates roughly 2.5 Exabytes of data every day** — this includes social media posts, emails, sensor readings, and video streams from across the globe. • One Exabyte equals 2^60 bytes; the prefix ‘exa’ comes from the Greek word for ‘six’ because it is 10^18 in decimal. • 💡 Option B (Yottabyte) is wrong because 1 YB = 1024 ZB, far larger than 1024 PB; Option C (Zettabyte) is wrong because 1 ZB = 1024 EB, not 1024 PB; Option D (Terabyte) is wrong because 1 TB is smaller than 1 PB, not larger.

Correct Answer: C. Petabyte

• **PB = Petabyte**, a storage unit equal to 1024 Terabytes, routinely used to quantify capacity in enterprise-grade storage systems, genomics databases, and astronomical research archives. • **‘Peta’ is an SI prefix meaning 10^15** — so one Petabyte in decimal terms equals one quadrillion bytes, which is why cloud providers use PB to describe warehouse-scale storage. • Scientific instruments like the Large Hadron Collider generate around 15 Petabytes of data annually from particle collision experiments. • 💡 Option A (PicoByte) is wrong because ‘pico’ means 10^-12, and PicoByte is not a real storage unit; Option B (ParaByte) is wrong because no such standard unit exists; Option D (Perabyte) is wrong because this term is not defined in any computing standard.

Correct Answer: C. Zettabyte

• **Zettabyte (ZB)** is the largest among the four options, equal to 1024 Exabytes or approximately 10^21 bytes — a scale so vast that the total data on the entire internet is measured in Zettabytes. • **‘Zetta’ is an SI prefix meaning 10^21** — by 2023 estimates, humanity had created roughly 120 Zettabytes of cumulative digital data, a number growing exponentially each year. • One Zettabyte could store all the words ever spoken by humans since the beginning of language, recorded in audio format. • 💡 Option A (Exabyte) is wrong because 1 EB = 1/1024 ZB, making it smaller; Option B (Petabyte) is wrong because 1 PB = 1/1024 EB, making it even smaller; Option D (Terabyte) is wrong because 1 TB is the smallest of all four options listed.

Correct Answer: C. Yottabyte

• **Yottabyte (YB) = 1024 Zettabytes**, currently the largest officially named unit in the International System of Units (SI), representing approximately 10^24 bytes of data. • **‘Yotta’ is the largest SI prefix, meaning 10^24** — to put it in perspective, storing 1 Yottabyte of data in hard drives would require more drives than atoms in a human body if each drive held 1 TB. • The IEC added Ronnabyte (RB) and Quettabyte (QB) above Yottabyte in 2022, as digital data growth demands ever-larger units. • 💡 Option A (Exabyte) is wrong because 1 EB = 1024 PB, far smaller than 1024 ZB; Option B (Petabyte) is wrong because 1 PB = 1024 TB, many orders of magnitude below 1024 ZB; Option D (Geopbyte) is wrong because it is an informal/unofficial term, not a recognized SI unit.

Correct Answer: D. Bit

• **Bit** = a binary digit that can hold only one of two values — 0 or 1 — representing the two mutually exclusive states of an electronic circuit (off/on, false/true, low/high). • **All digital data reduces to bits** — a photo, a song, or a video is ultimately stored as billions of 0s and 1s in a computer's memory or storage device. • Physical storage of bits uses different technologies: magnetic polarity in HDDs, electric charge in SSDs, and optical pits and lands on CDs. • 💡 Option A (Nibble) is wrong because a nibble is a group of 4 bits, not a single binary digit; Option B (Pixel) is wrong because a pixel is the smallest element of a display image, not a data unit; Option C (Byte) is wrong because a byte is a group of 8 bits.

Correct Answer: A. 4096 MB

• **4 GB = 4 × 1024 MB = 4096 MB**, because each Gigabyte contains exactly 1024 Megabytes in the binary system, so 4 GBs multiply out to 4096 MB of total RAM. • **This conversion matters for software compatibility** — a 32-bit operating system can only use up to 4096 MB (4 GB) of RAM even if more is installed, because its memory addresses top out at 2^32. • System benchmarks and task managers display memory in MB or GB, so knowing this conversion helps accurately interpret resource usage. • 💡 Option B (4000 MB) is wrong because it uses the decimal 1000 multiplier, not the binary 1024; Option C (4400 MB) is wrong because no standard conversion gives this result; Option D (4048 MB) is wrong because 4 × 1012 is not a binary unit calculation.

Correct Answer: C. Gigabyte

• **Gigabyte (GB)** is exactly 1024 times larger than a Megabyte, following the binary unit hierarchy where each step multiplies by 2^10 = 1024. • **GB is the dominant unit in modern consumer hardware** — RAM chips, smartphone storage, and SD cards are all standardly expressed in Gigabytes because it is the right scale for today's apps and media. • 1 GB = 1,073,741,824 bytes; this number comes from 2^30, which is 1024 × 1024 × 1024. • 💡 Option A (Terabyte) is wrong because 1 TB = 1024 GB, making it 1024 times larger than GB, not MB; Option B (Kilobyte) is wrong because 1 KB = 1/1024 MB, making it smaller than MB; Option D (Petabyte) is wrong because 1 PB = 1024 TB, far larger than 1024 MB.

Correct Answer: D. Kilobyte

• **Kilobyte (KB)** is the smallest among Megabyte, Terabyte, Gigabyte, and Kilobyte — because each larger unit is 1024 times its predecessor, making KB the lowest in this group. • **KB is used for tiny files** — plain text documents, configuration files, small icons, and cookie files are all measured in Kilobytes because they contain only a few thousand characters or less. • 1 KB = 1024 bytes = 8192 bits; this represents roughly 1000 characters of plain English text. • 💡 Option A (Megabyte) is wrong because 1 MB = 1024 KB, making it 1024 times larger; Option B (Terabyte) is wrong because 1 TB = 1024 GB = 1024^3 KB, enormously larger; Option C (Gigabyte) is wrong because 1 GB = 1024 MB = 1024^2 KB.

Correct Answer: C. Byte

• **Byte** = a collection of exactly 8 bits, making it the standard unit of digital data — this grouping emerged historically because 8 bits were the minimum needed to encode a full character set including uppercase letters, digits, and punctuation. • **Byte is the fundamental addressable unit of computer memory** — every RAM address points to one byte, which is why memory capacity is always expressed in multiples of bytes (KB, MB, GB). • With 8 bits, a byte can represent 2^8 = 256 distinct values, ranging from 0 to 255 in unsigned notation. • 💡 Option A (Nibble) is wrong because a nibble is only 4 bits, half a byte; Option B (Word) is wrong because a word size depends on CPU architecture (16/32/64 bits), not fixed at 8 bits; Option D (Record) is wrong because a record is a database concept, not a unit of memory.