Mixed MCQs

The Correct Answer is Magnetic Force.

• Magnetic resonance imaging ( MRI) is one of the most popular medical imaging methods used in the world at many diagnostic centers.
• These MRI scanners use strong magnetic fields, gradients of the magnetic field, and radio waves to produce images of the organs inside the body.
• The magnetic force is a component of the electromagnetic force, one of nature's four basic forces, which is induced by charge movement.
• There would be a magnetic force of attraction between two objects containing charge in the same direction of motion, while objects in charge traveling in opposite directions have between them a repulsive force.

The correct answer is chemical energy.

Key Points

• The dry cell is a type of electric battery which is used for portable electrical devices.
• Electricity is produced through the dry cells from electrochemical energy. Hence, Option 1 is correct.
• A common dry cell is a zinc-carbon cell.
• The electrolyte is immobilized as a paste by a dry cell, with just enough humidity in it to allow current to flow.
• Like a wet cell, a dry cell can work without spilling in any direction, because there is no free liquid in it.
• The versatility makes it ideal for mobile devices.
• The first wet-cell batteries, in comparison, were usually fragile glass containers featuring lead rods sticking from an open-top.
• Hence, they required careful handling to prevent spillage.
• The dry-cell battery development made a significant advance in battery safety and portability.
• Batteries render electricity from chemical energy.
• Batteries consist of one or more different parts, or cells, which contain an electrolyte called a chemical.
• Every cell has two electrodes that are electrically conductive immersed in its electrolyte.
• The electrodes consist of different materials; one releases electrons into the electrolyte, and the other absorbs them.
• Once an electrical system is attached to the electrodes, an electrical current passes through it and supports its operation with electric power.
• The energy contained in the dry cell is therefore in the form of chemical energy.

Additional Information

• Thermal energy
  • It is also called heat energy 
  • It is produced when a rise in temperature causes atoms and molecules to move faster and collide with each other.
  • The energy that comes from the temperature of the heated substance is called thermal energy.
  • Thermal energy is energy that comes from a substance whose molecules and atoms are vibrating faster due to a temperature rise.
• In physical sciences, mechanical energy
  • It is the sum of potential energy and kinetic energy.
  • It is the macroscopic energy associated with a system.
  • The principle of conservation of mechanical energy states that if an isolated system is subject only to conservative forces, then the mechanical energy is constant.
• Nuclear power
  • It is the use of nuclear reactions to produce electricity.
  • Nuclear power can be obtained from nuclear fission, nuclear decay, and nuclear fusion reactions.
  • Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium in nuclear power plants.

The correct answer is Tartaric acid.

• Tartaric acid is an organic acid that is white and crystalline.

Key Points

• It is found naturally in many fruits like grapes, bananas, tamarind, etc.
• This acid is added to foods as an antioxidant and to give its distinctive sour taste.
• Crystals and powders are prepared by a chemical process.
• It is also added to food for preservation.
• It is also a good antioxidant and is beneficial for kidneys.
• It helps to absorb minerals in the body.
• It is also helpful in controlling problems related to gases in the body.

The correct answer is Curvature of the lens.

Important Points

• Focal length of a lens depends on its curvature and the medium outside the lens.

Additional Information

• The ability of a lens to converge or diverge light rays depends on its focal length.
  • For example, a convex lens of short focal length bends the light rays through large angles, by focussing them closer to the optical centre.
  • Similarly, the concave lens of a very short focal length causes a higher divergence than the one with a longer focal length.
• The degree of convergence or divergence of light rays achieved by a lens is expressed in terms of its power.
  • The power of a lens is defined as the reciprocal of its focal length.

The correct answer is No weight.

Explanation:

• Gravity is a force that attracts a body toward the centre of the earth or any other mass-bearing physical body.

F = mg
where F is force, 
m is mass, and 
g is acceleration due to gravity.

• The weight of an object is the force that attracts it to the earth.
• A body that is free to fall under the influence of gravity is acted upon by the force of gravity.
• However, the object is not exerting any force on any surface. As a result, the weight of object is no weight (zero).

Concept:

• Food comprises constituents like proteins, carbohydrates, fats and supplementary substances such as minerals, vitamins and water that are vital for life.
• These constituents are known as nutrients. For proper functioning of our body, we need to consume bodybuilding foods (e.g. milk, meat, poultry, fish, eggs, pulses, groundnuts); energy-giving foods (e.g. cereals, sugar, roots, fats and oils); and protective foods (e.g. vegetables, fruits).

Explanation:

• Carbohydrates are the main source of energy for our body.
• Carbohydrates are of two types – simple and complex.
• Simple carbohydrates - These are quick-energy foods, e.g. sugar. Sources of simple carbohydrates are natural fruits, milk and milk products, and vegetables including potatoes and carrots.
• Complex carbohydrates - These are better sources of energy than sugar since they are released slowly. Sources of complex carbohydrates are bread, cereals (rice, wheat, bajra, corn, barley, ragi, sorghum, millets etc.),

Gram is not a source of carbohydrate, it is a source of protein.

Additional Information

Proteins:

• proteins are obtained from the animal as well as vegetable sources. Proteins of animal origin are found in milk, eggs, cheese, fish and meat.
• Proteins from these sources contain all the essential amino acids (EAA) in adequate amounts.
• Vegetable proteins are found in pulses (legumes), cereals, beans, nuts, oilseeds, etc

The correct answer is citric.

• Orange juice contains citric acid due to which tastes sour.

Key Points

• Fruits that contain citric acid are called citrus fruits.
• Citrus fruits are lemon, lime, orange, Grapefruit, etc.
• The formula of citric acid is C₆H₈O₇.

Additional Information

• Oxalic acid is found in tomato.
  • Its formula is C₂H₂O₄.
• Formic acid is found in the sting of ants and bees.
  • Its formula is CH₂O₂.
• Acetic acid is found in vinegar.
  • Its formula is id CH₃COOH.

• The blue litmus paper will turn red when it comes into contact with an acidic solution.
• When a litmus paper is put in a solution, depending on what the solution is, the indicator will react with the solution and will change its colour.
• On the other hand, red litmus paper reacts to alkaline substances by turning blue.
• Note: Acid will turn red litmus paper to red only.No change.

The correct answer is Bone-marrow.

Key Points

Red blood cell:

• Red blood cells (RBCs) are the most common type of blood cell and the vertebrate's principal means of delivering oxygen to the body tissues via blood flow through the circulatory system.
• RBC is formed in Bone Marrow.
• RBCs take up oxygen in the lungs, or in fish the gills, and release it into tissues while squeezing through the body's capillaries.
• The cytoplasm of erythrocytes is rich in hemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the red color of the cells and the blood.
• Each human red blood cell contains approximately 270 million of these hemoglobin molecules.
• The cell membrane is composed of proteins and lipids, and this structure provides properties essential for physiological cell function such as deformability and stability while traversing the circulatory system and specifically the capillary network.

Additional Information

• Red blood cells are thus much more common than the other blood particles: there are about 4,000–11,000 white blood cells and about 150,000 - 400,000 platelets per microliter.
• Human red blood cells take on average 60 seconds to complete one cycle of circulation.
• The blood's red color is due to the spectral properties of the hemic iron ions in hemoglobin.
• Each hemoglobin molecule carries four heme groups; hemoglobin constitutes about a third of the total cell volume.
• The normal pH range of blood is between 7.35 to 7.45. This means that blood is naturally slightly alkaline or basic.