FREE NEET MCQ Test Questions and Answers
Which of the following metal pollutants found in vehicle exhaust is the most hazardous?
Inefficient petroleum burning by automobiles contributes to 80% of the air pollution and 75% of the noise pollution in urban areas. They release lead (which accounts for 90% of all lead poisoning), ammonia, aldehydes, nitrogen oxides, carbon monoxide (77.2%), hydrocarbons (13.7%), and 7.7% of nitrogen oxides. Petroleum contains lead as the antiknock agents Pb(CH3)4 and Pb(C2H5)4.
A tuning fork with a frequency of 450 Hz resonates with a resonance air column that is 40 cm long. Without considering end adjustments, the speed of sound in air is:
We are aware that the fundamental mode of vibrations corresponds to the air column tube's minimal length. Therefore, by disregarded end corrections - Column length is 40 cm, or 0.4 meters. Tuning fork frequency is equal to 450 m The formula yields n = v/4I V = 450 4 0.4 = 720 m/s.
An increase in CO2 levels will result in:
Generally speaking, the air exchange taking place in your lungs increases the faster and deeper you breathe. This indicates that both the rate of blood oxygen intake and the rate of carbon dioxide washout have increased. Therefore, if you breathe quickly and deeply, the most amount of carbon dioxide will be removed from your blood. Consequently, the blood CO2 concentration dropped.
The corners of a cubic unit cell in a solid "AB" with a NaCl structure are occupied by "A" atoms. The solid's resulting stoichiometry is as follows if all the atoms with faces to one of the axes are eliminated:
Na in NaCl has eight corner and six face atoms, hence removing the face-centered atom of one axis results in the removal of two face atoms. A is therefore at 8 corners and 4 face centers. B is present in all octahedral voids, hence there are 12 1/4 + 1 = 4 B atoms per unit cell, which is equal to the number of A atoms per unit cell (8 1/8 + 4 1/2 = 3). Formula is therefore A3 B4.
Which of the following multicellular animals lacks neurons or nerve cells that can react to stimuli?
Unlike most animals, sponges don't have a nervous system or internal organs. Adult sponges cannot move, yet despite having no typical organs or sensory systems, they can respond to some physical stimuli. Sponges lack any ability to cognitively control their movement because they lack nerves and a brain. Thus, the appropriate choice is (B).
What is true about the following statements?
Chondrichthyes: These are streamlined marine creatures with cartilaginous endoskeletons. A placenta, which promotes the passage of nutrients and wastes between the mother's blood and the fetus, distinguishes a placental mammal (subclass Eutheria), any member of the mammalian group. All live mammals—aside from marsupials and monotremes—are classified as invertebrates. Cyclostomes are saltwater organisms that travel to freshwater to lay their eggs. Within a few days of spawning, they pass away. Their larvae re-enter the water after undergoing metamorphosis. Reptiles' kilons and testudos are incapable of maintaining a consistent body temperature.
A table tennis ball with a conducting tip on it hangs between two metal plates and is supported by a thin thread. One plate is connected to the earth, while the other is to a high-voltage generator, with the ball in between.
The tennis ball contacts the +ve plate after receiving a -ve charge from induction. Charges are then shared since they repel one another. As a result, the ball moves away and makes contact with an earthed plate, which imparts its charge before returning to its original place.
Which of the subsequent reagents can turn butanoic acid into butane?
By heating butanoic acid with hydriodic acid (HI) and red phosphorus, butane can be produced (Red P).
Cryolite is added to the charge in the electrolytic process of producing aluminium from refined bauxite in order to:
Cryolite is added to the charge in the electrolytic process of producing aluminum from refined bauxite because it lowers the melting point of bauxite (from 1200oC to 800o–900oC) and boosts the mixture's electrical conductivity. Thus, the appropriate choice is (B).
In the presence of an attacking reagent, the displacement of electrons in numerous bonds is known as:
When an attacking reagent is required, the electromeric effect is a transient effect that is activated. An intramolecular electron displacement causes the molecular polarizability effect known as the electromeric effect. It only has a fleeting impact.
Which of the following about the myelin sheath is incorrect?
The Schwann cell's (also known as neurilemmocyte's) outermost nucleated cytoplasmic layer, or neurilemma, surrounds the neuron's axon and is sometimes referred to as the neurolemma, sheath of Schwann, or Schwann's sheath. Since oligodendrocytes myelinate axons in the central nervous system, neurilemma is absent. Schwann cells produce oligodendrocytes in the central nervous system (CNS) and myelin in the peripheral nervous system (PNS: nerves) (CNS: brain and spinal cord). A single myelin sheath is formed by a single Schwann cell in the PNS.
Rhododendron leaves curling is one instance of?
The movement of a plant or a portion of a plant in response to a change in temperature is known as thermotropism or thermotropic movement. A typical illustration is how Rhododendron leaves will curl when it gets cold.
Which of the following is not an accurate differential?
Heat ′Q′ cannot be precisely discriminated because it is a path-dependent function; however, internal energy, entropy, and Gibbs free energy can be precisely differentiated since they are state functions.
Which of the subsequent antibody subtypes is produced by a peanut hypersensitive person?
Which of the subsequent antibody subtypes is produced by a peanut hypersensitive person? Allergy or hypersensitivity refers to the immune system's excessive reaction to specific environmental antigens. Allergens are chemicals that cause an immunological reaction of this type. These result in the production of lgE type antibodies. Dust mites, pollens, animal dander, and other common allergies are a few examples. Sneezing, watery eyes, a runny nose, and trouble breathing are all signs of allergic reactions. It occurs as a result of chemicals like serotonin and histamine.
What will the particles' X-coordinates be in a system of bodies where the center of mass is at the origin?
Assuming that the center of mass is at the origin, some particles will be located to the left and some to the right of the center of mass. The X-coordinate of particles that are farther to the left of the center of mass will be negative, whereas those that are farther to the right will be positive. Due to their homogeneous distribution around the body's center of mass, the particles in this scenario cannot always have positive X-coordinate values or always negative X-coordinate values.
The nitrogenous waste that is least hazardous is generated by:
Excretion is the process of eliminating waste products created by metabolic processes. Inside live cells, several biochemical processes take occur. These processes leave behind waste and toxic byproducts that are harmful to the body's cells and tissues. Compounds of carbon dioxide, ammonia, urea, uric acid, and other nitrogen are some toxic and excretory chemicals. Excretory organs are the unique organs that allow for the removal of these toxins from the body. The process of excreting uric acid is known as uricotelism. For species like birds and lizards that must conserve water for survival, the excretion of uric acid is helpful.