The full form of MODEM is

The correct answer is C, touchscreen. A touchscreen accepts a finger tap or a stylus stroke as input and displays the result on the very same surface, so the one piece of hardware performs both jobs. The modem, the network interface card and the hard disk belong to the same dual-role list.

Option A, the scanner, only reads a document or a photograph and feeds the image into the computer, which makes it a pure input device. Option B, the plotter, only draws the output the computer sends it and can take nothing back, so it is a pure output device. Option D, the light pen, is a photo-sensitive pointing device that selects an item by touching the screen, but the display it touches is a separate output device, so the pen itself is input only. Paper setters use exactly these three distractors, so remember the short dual-role list rather than reasoning about each option in the hall.

The correct answer is A, Douglas Engelbart. He built the first mouse, a small wooden box with a pair of wheels underneath, at the Stanford Research Institute, and the patent describes it as an X-Y position indicator for a display system. The name stuck because the wire coming out of the back looked like a tail.

Option B, Charles Babbage, designed the Difference Engine and the Analytical Engine in the nineteenth century and is called the Father of the Computer, a completely different title. Option C, Jack Kilby, demonstrated the first integrated circuit and belongs to the generations chapter, not to input devices. Option D, Christopher Latham Sholes, perfected the mechanical typewriter and gave us the QWERTY keyboard layout, so he is the right answer to a keyboard question and a tempting wrong one here. Keep one invention fixed against each name.

The correct answer is C, dot matrix printer. Its print head carries a column of tiny pins that strike an inked ribbon against the paper, forming each character out of dots. Because the strike passes through the paper, a dot matrix printer can print carbon copies in one go, and it is noisy for the same reason.

Option A, the laser printer, uses a laser beam, a photosensitive drum and dry toner fused by heat, and nothing ever strikes the page. Option B, the inkjet, sprays extremely fine droplets of liquid ink onto the paper without contact. Option D, the thermal printer, heats chemically treated paper so that the characters appear, which again involves no impact. All three are non-impact printers. The one-line rule for the exam is that only the dot matrix, the daisy wheel and the line printers strike the paper.

The correct answer is A, processing of bank cheques. MICR stands for Magnetic Ink Character Recognition. The line of characters printed along the foot of a cheque is set in magnetic ink in the E-13B font, and the reader identifies each character from its magnetic signal, so the cheque is sorted correctly even when it has been folded, stamped or soiled.

Option B, reading objective answer sheets, is the work of OMR, the Optical Mark Reader, which simply detects whether a mark has been made in a fixed position. Option C, billing at a retail counter, is done by a barcode reader that decodes the bar pattern printed on the packet. Option D, recording fingerprints, is the work of a biometric scanner. Banking papers return to MICR every year, so tie it firmly to the cheque and to the E-13B font.

The correct answer is B, pixel. The word is a contraction of picture element. A screen image is a grid of these points, and the number of them across and down the screen is what is quoted as the resolution of the monitor, so a higher pixel count means a finer picture.

Option A, the bit, is the smallest unit of data, a single binary digit, not a unit of a picture, and eight of them make a byte. Option C, the byte, is the unit in which memory and file sizes are measured. Option D, dot pitch, is a real term from the same chapter but it means something else: it is the distance between two neighbouring dots of the same colour on the screen, measured in millimetres, and a smaller dot pitch gives a sharper display. Examiners like to place pixel and dot pitch in the same set of options, so read the stem carefully.