Explanation

Systematic errors are caused by faulty or improper functioning of instruments, or by a flaw in the experimental design.

These errors are consistent and repeatable, and can be identified and corrected.

Explanation

When the magnitude of Kc (equilibrium constant) is small, it indicates that the reaction mixture contains mostly reactants, and the forward reaction does not proceed very far.

Explanation

Vaccination can be administered:

• Before infection (preventive vaccination, the most common scenario)
• After infection (post-exposure prophylaxis, PEP, to prevent severe symptoms or complications)
• During infection (in some cases, to reduce disease severity and transmission, like during an outbreak or pandemic)

Explanation

When CO2 levels in the blood increase, it triggers a response in the brain's respiratory centers to increase the rate of breathing.

This is because high CO2 levels indicate that the body is producing more waste products and needs to expel them through exhalation.

Explanation

The main source of energy in stars is nuclear fusion.

It is the process of combining atomic nuclei (usually hydrogen nuclei) to form a heavier nucleus, releasing vast amounts of energy in the process.

This energy is what makes stars shine.

Explanation

Ultrasound has several medical applications, including:

• Pre-natal scanning
• Diagnostic imaging
• Cancer treatment

In industry, ultrasound is used for:

• Cleaning and deburring
• Welding and bonding
• Non-destructive testing

Explanation

The permanent hardness of water is due to the presence of MgSO₄ (magnesium sulfate).

Permanent hardness is caused by dissolved minerals like calcium sulfate (CaSO₄) and magnesium sulfate, which cannot be removed by boiling the water.

Explanation

The head of the femur (thigh bone) attaches to the acetabulum, a cup-like structure in the pelvis.

The acetabulum is formed by the fusion of three bones: the ilium, ischium, and pubis.

This joint is known as the hip joint or coxofemoral joint.

Explanation

The work done on a unit charge against an electric field intensity is called electric potential.

It is also known as voltage or potential difference.

It is measured in volts (V) and represents the energy transferred per unit charge.

Electric potential (V) = Work done (W) / Charge (Q)

V = W / Q

Explanation

X-rays are a type of electromagnetic radiation that are commonly used in radiotherapy to destroy cancer cells.

They have enough energy to penetrate deep into tissue and damage the DNA of cancer cells, slowing their growth or killing them.