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Assertion :- In fish ammonia is excreted...

Assertion `:-` In fish ammonia is excreted by diffusion through gill surface as ammonium ions.
Reason `:-` Some amount of urea may be retained in the kidney matrix of some animals to maintain a desired osmolarity.

A

If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion .

B

If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion

C

If Assertion is True but the Reason is False.

D

If both Assertion & Reason are false.

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The correct Answer is:
To solve the assertion and reason question, we will analyze both the assertion and the reason separately, and then determine their validity and relationship. ### Step-by-Step Solution: 1. **Understanding the Assertion:** - The assertion states that in fish, ammonia is excreted by diffusion through the gill surface as ammonium ions. - Fish are known to be ammonotelic, meaning they primarily excrete ammonia, which is a toxic byproduct of protein metabolism. - Ammonia is indeed excreted through the gills into the surrounding water via diffusion, and it can exist as ammonium ions (NH4+). - **Conclusion:** The assertion is **true**. 2. **Understanding the Reason:** - The reason states that some amount of urea may be retained in the kidney matrix of some animals to maintain a desired osmolarity. - Many terrestrial animals, including mammals, excrete urea as a waste product. To maintain osmotic balance, they may retain some urea in their kidneys. - This retention helps regulate osmolarity in the body fluids. - **Conclusion:** The reason is also **true**. 3. **Analyzing the Relationship:** - The assertion specifically discusses the excretion of ammonia in fish, while the reason discusses urea retention in the kidneys of other animals. - The two statements are true, but the reason does not explain the assertion. The assertion is about ammonia excretion in fish, whereas the reason pertains to urea in different animals. - **Conclusion:** The reason is not a correct explanation of the assertion. 4. **Final Answer:** - Both the assertion and the reason are true, but the reason is not the correct explanation for the assertion. Therefore, the correct answer is option two: "Both assertion and reason are true, but reason is not the correct explanation of assertion."
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When an atom or an ion is missing from its nomal lattice site a lattice vacanecy (Schottky defect) is created. In stoichmeteric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charge ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This id the Frenkel defect commonly found along with the Schottky defects and interstitial. In pure alkali halides. Frenked defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unike Schottky defects, Frenkel defect do not change the density of the solids. in certain ionic solids (e.g., AgBr) both schottky and Frenkel defect occur. The Defects idiscussed above do not disturb the stoichiometery of the crystalline material. there is large variety of non-stoichiometric inorganic solids which contains an excess or deficienty of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an important group of solids. For example in the vanadium oxide, VO_(x),x can be anywehere between 0.6 and 1.3 there are solids such as difficult to prepare in the soichiometric omposition thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a compositiion of Fe(0.95) O but it may range from Fe_(0.93) O to Fe_(0.96)O ). Non-stoichiometric behavious is most commonly found for transition metal compounds through is also known for some lathanoids and actinoids. Zinc oxide loses oxygen reversible at high temperature and turns yellow in colour. the excess metal is accomodated interstitial, giving rise to electrons trapped in the neighbourhood, the enchanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons. Anion vacancies in alkali halides are produced by heating the alkali halid crystals in an atmosphere of the alkali metal vapour. when the metal atoms deposit on the surface they diffuse into the cystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped i anion vacancies are referred to as F-centers (From Farbe the German word for colouf) that gives rise to interesting colour in alkali halides. Thus, the excess of potassium i KCl makes the crystal appear violet and the excess of lithium in LiCl makes it pink. Which of the following is most appropritate crystal to show Fremkel defect ?

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When an atom or an ion is missing from its normal lattice site, a lattice vacancy (Schottky defect) is created. In stoichimetric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charged ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This is the Frenkel defect commonly found along with the Schottky defects and interstitials. In pure alkali halides, Frenkel defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unlike Schottky defects, Frenkel defects do not change the denstiy of the solids. In certain ionic solids (e.q. AgBr) both Schottky and Frenkel defects occur. The defects discussed above do not disturb the stoichiometry of the crystalline material. There is large variety of non-stoichiomertic inorganic solids which contain an excess or deficiency of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an inmportant group of solids. For example in the vanadium oxide, VO_(x) , x can be anywhere between 0.6 and 1.3. There are solids which are difficult to prepare in the stoichiometric composition. Thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a composition of Fe_(0.95)O but it may range from Fe_(0.93)O " to " Fe_(0.96)O ). Non-stoichiometric behaviour is most commonly found for transition metal compounds though is also known for some lanthanoids and actinoids. Zinc oxide loses oxygen reversibly at high temperature and turns yellow in colour. The excess metal is accommodated interstitially, giving rise to electrons trapped in the neighbourhood. The enhanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons.ltrbgt Anion vacancies in alkali halides are produced by heating the alkali halide crystals in an atmosphere of the alkali metal vapur. When the metal atoms deposit on the surface they diffuse into the crystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped in anion vacancies are referred to as F-centers (from Farbe the German word for colour) that given rise to interesting colour in alkali halides. Thus, the excess of potassium in KCl makes the crytal appear violet and the excess of lithium in LiCl makes it pink. When LiCl is heated into the vapour of lithium, the crystal acquires pink colour. This is due to

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