How many contacts does the RJ-45 connector used for Ethernet networking have?

The correct answer is A, Universal Serial Bus. The standard first appeared in 1996 and was meant to replace the many different ports of an older computer with one socket for every kind of peripheral. It is called serial because it sends one bit at a time, universal because the same port serves a keyboard, a printer, a camera or a storage device, and a bus because many devices share the one path, up to a hundred and twenty-seven of them through hubs. Option B is wrong because the middle word is serial, not system, and a system bus is the internal path between the processor and memory, a different idea altogether. Option C is wrong because the first word is universal, not unified. Option D is wrong because USB is not limited to storage, even though pen drives are its commonest use.

The correct answer is B, fifteen. The Video Graphics Array connector is a D-shaped plug with fifteen pins in three rows of five, usually coloured blue, and it carries an analogue video signal only, so a separate cable is needed for sound. Option A is wrong because nine pins belong to the DB-9 serial connector of the RS-232 standard, known to the operating system as the COM port. Option C is wrong because nineteen pins belong to the standard Type-A HDMI connector, which carries digital video and audio together; mixing up the fifteen of VGA with the nineteen of HDMI is the usual mistake in this question. Option D is wrong because twenty-five pins belong to the DB-25 parallel or LPT connector, which was used for printers on older computers.

The correct answer is C, HDMI. The High-Definition Multimedia Interface carries high-definition digital video and multi-channel digital audio in the same cable, which is why one HDMI lead is enough to join a computer to a television or a projector. Option A is wrong because the Video Graphics Array port carries an analogue video signal only and needs a separate audio cable, a difference that is asked again and again. Option B is wrong because the PS/2 port is a six-pin socket for a keyboard or a mouse and carries no video or audio at all. Option D is wrong because the serial port sends one bit at a time at low speed and was used for modems and instruments, not for display. DisplayPort is the other port that carries both video and audio, chiefly on computer monitors.

The correct answer is A, because that statement is the false one. Unshielded twisted pair cable has no metal foil or braid around its pairs, so it resists electromagnetic interference less well than shielded twisted pair, not better; the only protection it has is the twisting of each pair, which cancels much of the noise picked up by the two wires. Option B is a true statement, since UTP is the cable of almost every office and home local area network, in grades such as Cat 5e and Cat 6. Option C is also true: without the shield the cable is thinner, lighter and easier to bend around corners, which is one reason installers prefer it. Option D is true as well, because UTP is cheap to buy and to terminate and performs well over the hundred-metre segment that Ethernet allows.

The correct answer is B, the keyboard. A computer with PS/2 ports has two six-pin mini-DIN sockets that are identical in shape, so they are distinguished by colour: purple for the keyboard and green for the mouse. Plugging the devices into the wrong sockets leaves them unrecognised, which is why the colour code was introduced at all. Option A is wrong because the mouse socket is the green one, and this swap is exactly what the question tests. Option C is wrong because a printer was connected through the twenty-five-pin parallel or LPT port, and is connected through USB today; it never used a PS/2 socket. Option D is wrong because a microphone goes into the pink 3.5 millimetre audio jack, while green among the audio jacks means the speaker or line output, a second colour code worth learning separately.