Manage hardware resources: This is the core function of an operating system. The OS acts as an intermediary between the user and the computer hardware, managing resources such as the CPU, memory, disk drives, and peripherals to ensure that software applications run smoothly.

The speed of a computer processor is measured in Gigahertz (GHz).

• Gigahertz (GHz): This is the most common unit used to measure the clock speed of a computer processor. It indicates how many cycles per second the processor can execute, with 1 GHz being equal to 1 billion cycles per second. The higher the GHz, the faster the processor can process instructions.

Why Other Options are Incorrect:

• (a) BPS (Bits Per Second): This is used to measure data transfer speed, not the processor speed.
• (c) Baud: This is used in telecommunications to measure the rate of signal change, not the speed of a processor.
• (d) MIPS (Million Instructions Per Second): While MIPS is sometimes used to measure a processor's performance, it’s not as common as GHz for describing processor speed.

Master Slide: The Master Slide in PowerPoint serves as a template that controls the overall design, layout, and formatting of all the slides in a presentation. When you make changes to the Master Slide, those changes automatically apply to all slides associated with that Master. This is useful for maintaining consistency in fonts, colors, backgrounds, and other design elements throughout the presentation.

The correct Excel function used to look up a value in a table based on the first column is VLOOKUP.

• VLOOKUP stands for "Vertical Lookup." It is used to search for a value in the first column of a table and return a value in the same row from another column you specify.
• The function works by searching vertically down the first column of the specified range to find the lookup value, and then it retrieves the corresponding value from the specified column within the same row.

Why Other Options are Incorrect:

• (b) HLOOKUP: This function is similar to VLOOKUP but is used for horizontal lookups. It searches for a value in the first row of a table and returns a value from the same column in a specified row.
• (c) A1LOOKUP and (d) ALOOKUP: These functions do not exist in Excel.

Firewall: A firewall is a security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a trusted internal network and untrusted external networks, such as the internet.

Purpose: The firewall filters the data packets, allowing or blocking them based on security criteria, thereby protecting the network from unauthorized access, cyber attacks, and other threats.