Every free question on Computer Awareness & Technology (General Science) from past WBCS Preliminary Examination and WBCS Main Examination papers, newest first, each with its answer and a short explanation. Free to read.
Answer: (C) 1 to 100
Nanoparticles are conventionally defined as particles with at least one dimension between 1 and 100 nanometres. 100–1000 nm is the sub-micron range, and 0.1–10 nm or 0.01–1 nm reach down to atomic sizes.
Answer: (B) 4 GHz
C-band satellite links use about 6 GHz for the uplink and about 4 GHz for the downlink. 14 GHz and 11 GHz are the Ku-band uplink and downlink, and 2 GHz is S-band.
Answer: (A) Simplex
In broadcast TV, signals flow only from the station to the viewer, which is simplex (one-way) transmission. Half-duplex (walkie-talkie) and full-duplex (telephone) both allow two-way communication.
Answer: (D) All of the above
Industrial robots are used to reduce labour needs, raise productivity through consistent fast work, and run machines more evenly so they last longer. Since all three are stated aims, (D) is the answer rather than any single one.
No option is correct as printed — this question is disputed. WBPSC awarded the mark to all candidates: two correct options — India uses both AM (MW/SW) and FM for radio broadcasting.
Radio broadcasting in India uses both amplitude modulation (All India Radio's medium- and short-wave services) and frequency modulation (FM stations), so (A) and (B) are both correct. The Commission therefore awarded the mark to all candidates.
Answer: (D) Bugs
An error or fault in a computer program is called a 'bug', and finding and removing it is 'debugging'; the term became popular after Grace Hopper's team found a moth stuck in the Harvard Mark II computer in 1947. Spam is unwanted bulk e-mail, and a virus is a malicious program that copies itself and damages data. Errors may be syntax errors, logical errors or run-time errors.
Answer: (B) Secondary
Primary memory is the main memory used directly by the CPU (RAM, which is volatile, and ROM). Secondary storage holds data permanently outside the main memory: hard disk, SSD, CD/DVD, memory card and USB pen drive, so a USB drive is a secondary storage device (it uses flash memory). Tertiary storage refers to removable mass storage such as magnetic tape libraries used for archives and backup.
Answer: (D) byte
The printed key gives 'byte', but by standard definition 1 byte = 8 bits and 1 nibble = 4 bits, so 16 bits make 2 bytes. A group of 16 bits is conventionally called a 'word' (the word length depends on the processor: 16 bits on a 16-bit machine, 32 or 64 bits on later ones). Units to remember: 1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB, 1 TB = 1024 GB.
Answer: (B) Wink
LinkedIn (professional networking, launched 2003, now owned by Microsoft), Facebook (2004) and Google Plus (Google's social network, launched 2011 and closed for consumers in 2019) are social networking sites. 'Wink' is not a social networking site, so it is the odd one out. Other social media names for exams: Twitter (now X), Instagram, WhatsApp, Telegram.
Answer: (A) Java
Android, the mobile operating system developed by Google on the Linux kernel, has traditionally used Java for app development; Google made Kotlin an official language in 2017 and its preferred language in 2019. C and C++ can be used only for special native parts of an app, and PHP is a server-side scripting language for websites. Apple's iOS apps are written in Swift or Objective-C.
