RRB JE 2025 Previous Year GK Questions with Answers

The correct answer is B, 010010. The 2's complement of a binary number is found in two steps: flip every bit to get the 1's complement, then add 1. Flipping 101110 gives 010001, and 010001 + 1 = 010010. A quick check confirms it: 101110 is 46 and 010010 is 18, and 46 + 18 = 64, which is 2⁶ for a six-bit number, exactly as it should be. Computers use the 2's complement to store negative numbers and to do subtraction by addition, which keeps their circuits simple. A shortcut also works: copy the bits from the right up to and including the first 1, then flip all the rest. A is wrong because 010011 adds 2 instead of 1 to the 1's complement. C is wrong because 110001 leaves the leftmost bit unflipped. D is wrong because 010001 is only the 1's complement; the final +1 is missing. Exam tip: 2's complement = flip all bits, then add 1; a number plus its 2's complement equals 2ⁿ.

The correct answer is B, To prevent unauthorised access to a private network. A firewall stands between a trusted private network and an untrusted one such as the internet, and checks the data going in and out. Traffic that matches its security rules is allowed and the rest is blocked, much like a guard at a gate. It can be hardware, such as a separate device or a feature of a router, or software, such as the firewall built into Windows. The name comes from the fire-resistant walls in buildings that stop a fire from spreading from one part to another. A is wrong because a firewall does not make the connection faster; checking traffic can even slow it slightly. C is wrong because finding and removing viruses is the job of antivirus software, which works on files already on a computer. D is wrong because storing passwords safely is the work of a password manager. Exam tip: firewall = gatekeeper of network traffic; antivirus = cleaner of infected files.

The correct answer is A, SRAM. Static RAM stores each bit in a flip-flop circuit made of several transistors, usually six, so the bit stays put as long as the power is on and never needs refreshing. That makes SRAM very fast, but also costly and bulky, so it is used in small amounts as cache memory inside the processor. Both kinds of RAM are volatile and lose their data when the power goes off. B is wrong because DRAM stores each bit as a charge in a tiny capacitor that slowly leaks, so it must be refreshed every few milliseconds; it is cheaper and denser, and serves as the main memory. C is wrong because flash memory is non-volatile storage used in pen drives, memory cards and SSDs, and it is slower than RAM. D is wrong because ROM is read-only, non-volatile memory that holds start-up instructions, not a type of RAM. Exam tip: SRAM = static, fast, no refresh, used as cache; DRAM = dynamic, needs refresh, used as main memory.

The correct answer is D, Hard Disk. A hard disk is a secondary storage device that keeps programs and files permanently, even when the power is off, and it sits outside the processor. The CPU (Central Processing Unit), often called the brain of the computer, is made of the Arithmetic Logic Unit, the Control Unit and a set of small, very fast registers. Modern processors also carry cache memory on the same chip to hold the data and instructions they need most often. Data from the hard disk is first loaded into RAM, then moved into the cache and registers before the CPU works on it. A is wrong because the ALU does all arithmetic and logical work such as addition and comparison. B is wrong because the Control Unit fetches and decodes instructions and directs every operation. C is wrong because cache memory is built into the processor chip and is the fastest memory after the registers. Exam tip: CPU = ALU + CU + registers (with cache); hard disk = secondary storage.

The correct answer is A, F5. In Microsoft PowerPoint, pressing F5 starts the slide show from the first slide, whichever slide you are working on at that moment. The same command sits on the Slide Show tab as 'From Beginning'. Its close partner is Shift + F5, which starts the show from the current slide, and paper setters like to place the two side by side. During the show, Esc ends the presentation, and pressing B or the full stop key turns the screen black until you press it again. B is wrong because Alt + Tab switches between open windows in Windows. C is wrong because Ctrl + P opens the Print option in almost every Office program. D is wrong because Shift + F5 begins the show from the current slide, not from the beginning. Exam tip: F5 = start from the beginning, Shift + F5 = start from the current slide, Esc = end the show.