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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Related Questions
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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Correct Answer is D
Explanation
This reaction involves an acid (hydrochloric acid, HCl) and a base (magnesium hydroxide, Mg(OH)₂) reacting to form water (H₂O) and a salt (magnesium chloride, MgCl₂). This is a classic neutralization reaction, where an acid reacts with a base to neutralize each other, producing water and a salt.
- Neutralization Reaction: Acid + Base → Water + Salt
- In this case:
- Acid: HCl (hydrochloric acid)
- Base: Mg(OH)₂ (magnesium hydroxide)
- Products: H₂O (water) and MgCl₂ (magnesium chloride)
The other options do not apply:
- A. Decomposition: A single compound breaks down into two or more substances. Not the case here.
- B. Combustion: A substance reacts with oxygen, often producing heat and light (usually with organic compounds). Not the case here.
- C. Synthesis: Two or more substances combine to form a single product. Not applicable to this reaction.
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 D
Explanation
This reaction is exothermic (releases heat), as indicated by the presence of "Heat" on the product side (C + Heat). According to Le Chatelier's Principle, when the temperature of an exothermic reaction is increased, the equilibrium shifts to counteract the added heat by favoring the reverse reaction (where heat is absorbed).
- As a result, the system will shift towards the left (toward the reactants, A and B), to consume the excess heat.
- Therefore, the concentrations of A and B will increase, and the concentration of C will decrease.
The other options do not align with this behavior:
- A. Incorrect, as the concentration of C will change (decrease).
- B. Incorrect, the reaction will shift away from equilibrium due to the temperature change.
- C. Incorrect, the concentration of C will not increase; it will decrease.
Correct Answer is A
Explanation
Innate immunity is the first line of defense against pathogens and is present at birth. It provides immediate, non-specific protection against a wide range of pathogens, including bacteria, viruses, and fungi. Innate immunity involves physical barriers, such as skin and mucous membranes, as well as cellular and molecular components, such as phagocytes and cytokines.
Adaptive immunity, on the other hand, is developed over time and provides specific protection against particular pathogens. It involves the recognition of antigens, which are specific components of pathogens, by immune cells called lymphocytes. The lymphocytes then produce antibodies that are specific to the antigens, allowing for a targeted response to the pathogen. This process takes time to develop, as the immune system needs to encounter the pathogen and mount a response.
Overall, innate immunity provides immediate, non-specific protection while adaptive immunity provides specific protection that is tailored to the particular pathogen. Both forms of immunity work together to protect the body against pathogens.
Correct Answer is B
Explanation
Transcription is the process by which DNA is copied into RNA. During transcription, the DNA molecule unwinds and RNA polymerase reads the DNA sequence and synthesizes a complementary RNA molecule using the DNA as a template.
Correct Answer is D
Explanation
The unit used to indicate length is the meter (m). It is the base unit of length in the International System of Units (SI).
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 C
Explanation
The three major pairs of salivary glands are the parotid glands, sublingual glands, and submandibular glands.
- Parotid glands are located just in front of your ears.
- Sublingual glands are located below either side of your tongue, under the floor of your mouth.
- Submandibular glands are located below your jaw.
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Correct Answer is C
Explanation
Stomach acid is highly acidic, primarily composed of hydrochloric acid (HCl), which means it has a low pH (around 1 to 3). Acids release hydrogen ions (H⁺) in solution, which lowers the pH.
- A. It has a higher pH: Incorrect, as acidic solutions have a lower pH compared to neutral distilled water (which has a pH of 7).
- B. It contains nitrogen: Incorrect, stomach acid is composed mostly of HCl, not nitrogen-containing compounds.
- D. It has more hydroxyl ions: Incorrect, acidic solutions have fewer hydroxyl ions (OH⁻); hydroxyl ions are more common in basic (alkaline) solutions.
In comparison to distilled water, which is neutral, the stomach acid solution has significantly more hydrogen ions, making it more acidic.
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