What is the chemical formula for water?
H2O
CO2
NaCl
C6H12O6
Correct Answer : A
The chemical formula for water is H2O. It consists of two hydrogen atoms and one oxygen atom.
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Correct Answer is C
Explanation
A frameshift mutation is a type of genetic mutation that involves the insertion or deletion of one or more nucleotides in a DNA sequence. This can cause a shift in the reading frame of the genetic code, resulting in a change in the amino acid sequence of the resulting protein. Frameshift mutations can have significant effects on the function of the protein and can lead to genetic disorders or diseases.
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Correct Answer is B
Explanation
In the given exothermic reaction:
CaO + H2O ⇌ Ca(OH)2 + heat
To increase the total yield of lime water (Ca(OH)â‚‚), you can apply Le Chatelier's Principle, which states that if a dynamic equilibrium is disturbed, the system will shift in a direction that counteracts the disturbance.
- A. Continuously remove Ca(OH)â‚‚: By removing the product (Ca(OH)â‚‚) as it forms, the equilibrium will shift to the right, favoring the formation of more Ca(OH)â‚‚. This is the most effective way to increase the yield.
The other options are less effective or counterproductive:
- B. Increase the temperature: Since the reaction is exothermic, increasing the temperature would shift the equilibrium to the left (toward the reactants), reducing the yield of Ca(OH)â‚‚.
- C. Increase the pressure: This reaction does not involve gases, so changing the pressure would not significantly affect the equilibrium.
- D. Add an enzyme that can catalyze this reaction: While a catalyst speeds up the rate of reaction, it does not affect the equilibrium position or the total yield of products. It simply allows the system to reach equilibrium faster.
Thus, continuously removing Ca(OH)â‚‚ is the best way to increase the total yield of lime water.
Correct Answer is A
Explanation
The three germ layers that form during embryonic development are the ectoderm, mesoderm, and endoderm. The ectoderm is the outermost layer, and it gives rise to the skin, hair, nails, and nervous system. The nervous system develops from a specialized region of the ectoderm called the neural plate, which invaginates to form the neural tube. The neural tube ultimately gives rise to the brain and spinal cord, which make up the central nervous system, as well as the peripheral nervous system. The endoderm gives rise to the lining of the digestive and respiratory tracts, while the mesoderm gives rise to the musculoskeletal system, circulatory system, and several other organs. The exoderm is not a germ layer and does not exist during embryonic development.

Correct Answer is A
Explanation
Innate immunity and adaptive immunity are two arms of the immune system that work together to protect the body from pathogens. Innate immunity is the first line of defense and is present at birth. It includes physical and chemical barriers such as the skin, mucous membranes, and antimicrobial peptides, as well as cells such as macrophages and natural killer cells that can quickly recognize and atack pathogens. Innate immunity is nonspecific, meaning it responds to a wide variety of pathogens in a similar way.
Adaptive immunity, on the other hand, is acquired after exposure to pathogens. It involves the production of antibodies and activation of T cells, which are specific to particular pathogens. Adaptive immunity takes longer to develop than innate immunity, but it provides a more specific and targeted response to pathogens. Once the adaptive immune system has been activated against a particular pathogen, it can provide long-term protection against future infections with that pathogen.
Option b) is incorrect because innate immunity is nonspecific while adaptive immunity is specific. Option c) is incorrect because antibodies are a part of adaptive immunity while T cells can be a part of both innate and adaptive immunity. Option d) is incorrect because adaptive immunity can provide long-term protection, while innate immunity provides immediate but short-lived protection.
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Correct Answer is A
Explanation
The chemical formula for water is H2O. It consists of two hydrogen atoms and one oxygen atom.
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Correct Answer is B
Explanation
Exothermic reactions are reactions that release energy in the form of heat, light, or sound. Burning wood is an example of an exothermic reaction because it releases heat and light. As the wood reacts with oxygen in the air, it undergoes a combustion reaction that releases energy in the form of heat and light. Melting ice is an endothermic reaction because it requires energy input to melt the solid ice into liquid water. Cooking an egg is a chemical reaction that involves denaturing the proteins in the egg, but it is not necessarily exothermic or endothermic. Dissolving sugar in water is also not an example of an exothermic reaction because it does not release energy in the form of heat, light, or sound.

Correct Answer is A
Explanation
The diaphragm is a dome-shaped muscle that plays a key role in breathing. It separates the thoracic cavity, which contains the heart and lungs, from the abdominal cavity. When the diaphragm contracts, it moves downward and increases the volume of the thoracic cavity, allowing air to flow into the lungs. When it relaxes, it moves upward and decreases the volume of the thoracic cavity, forcing air out of the lungs.
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Correct Answer is A
Explanation
Electrons are subatomic particles that possess a very small mass compared to protons and neutrons. The mass of an electron is approximately 11836of the mass of a proton or neutron, making it negligible when calculating the atomic mass of an atom.
In atomic mass calculations, protons and neutrons are considered because they make up the bulk of the atom's mass:
- Proton: Positively charged, and each proton has a mass of about 1 atomic mass unit (amu).
- Neutron: Neutral charge, with a mass also close to 1 amu.
- Electron: Negligible mass, contributing very little to the atomic mass, which is why the atomic mass number is typically determined by the number of protons and neutrons.
Quarks are the fundamental constituents of protons and neutrons but are not typically referred to in terms of atomic mass.
Correct Answer is B
Explanation
The mitral valve is located between the left atrium and left ventricle of the heart and helps to regulate the flow of blood between these chambers. It consists of two leaflets or flaps that open and close in response to changes in pressure as the heart beats.
During diastole, when the heart is relaxed and filling with blood, the mitral valve opens to allow blood to flow from the left atrium into the left ventricle. During systole, when the heart contracts to pump blood out of the left ventricle and into the systemic circulation, the mitral valve closes to prevent backflow of blood into the left atrium.
The mitral valve is one of four valves in the heart that help to ensure the unidirectional flow of blood through the heart and the rest of the circulatory system. Problems with the mitral valve, such as mitral valve prolapse or mitral stenosis, can lead to a range of symptoms and complications, including shortness of breath, fatigue, chest pain, and heart failure.
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Correct Answer is A
Explanation
Transfer RNA (tRNA) is responsible for carrying amino acids to ribosomes during protein synthesis. Each tRNA molecule has a specific anticodon that matches a codon on the messenger RNA (mRNA) molecule. The tRNA molecule binds to the mRNA codon and brings the corresponding amino acid to the ribosome, where it is added to the growing polypeptide chain.
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