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[A] : Pearl is formed when a foreign par...

[A] : Pearl is formed when a foreign particle gets in between shell and mantle .
[R] : The inner nacreous layer called mother of pearl is formed by layers of `CaCO_(3)` and concholin.

A

If both A and R are true and R is the correct explanation of A

B

If both A and R are true but R is not the correct explanation of A

C

If A is true and R is false

D

If both A and R are false

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Pearl is secreted when a foreign particle happens to enter between

[A] : When a foreign object , such as a sand grain gets in between the shell and mantle , it results in the formation of a pearl . [R] : The inner nacreous layer of irridiscent nacre is called the mother of pearl which is formed by many thin and alternating layers of calcium carbonate and concholin .

Pearl is formed when a foreign substance gets trapped between A of B (a) A- Shell and mantle B - Pila (b) A- Nacreous and prismatic layer B-Pinctada (c) A - Shell and mantle B Pinctada (d) A- Nacreous and prismatic layer B- Ostrea

The method of induction of foreign particles between the mantle and the shell of pearl oyster for the simulation of pearl formation was introduced in Japan by

On fusion of a mixture of Na_2CO_3 and CaCO_3 with silica at 1500^@C , a liquid consisting of silicates of sodium and calcium is formed. On cooling . Liquid become viscous and eventually ceases to flow . It becomes solid and is known as glass. By varying the proportions of the three basic ingredients and by adding other substances, the properties of glass can be altered, Glass can be represented as R_2 O. MO.6SiO_2 , where R= Na or K, M = CaBa, Zn or PbSiO_2 may be replaced by Al_2 O_3 , B_2 O_3 or P_2 O_5 . Coloured glasses are obtained by adding certain metallic oxides or salts in the fused mass, Glass is attached by HF and this property is used to make marking on the glass , This is known as etching . The glass on rapid cooling becomes brittle and fragile . The articles of glass are cooled neither slowly nor very rapidly . The process of gradual cooling of glass is called annealing . Glass is .

On fusion of a mixture of Na_2CO_3 and CaCO_3 with silica at 1500^@C , a liquid consisting of silicates of sodium and calcium is formed. On cooling . Liquid become viscous and eventually ceases to flow . It becomes solid and is known as glass. By varying the proportions of the three basic ingredients and by adding other substances, the properties of glass can be altered, Glass can be represented as R_2 O. MO.6SiO_2 , where R= Na or K, M = CaBa, Zn or PbSiO_2 may be replaced by Al_2 O_3 , B_2 O_3 or P_2 O_5 . Coloured glasses are obtained by adding certain metallic oxides or salts in the fused mass, Glass is attached by HF and this property is used to make marking on the glass , This is known as etching . The glass on rapid cooling becomes brittle and fragile . The articles of glass are cooled neither slowly nor very rapidly . The process of gradual cooling of glass is called annealing . Ordinary glass is .

On fusion of a mixture of Na-2CO_3 and CaCO_3 with silica at 1500^@C , a liquid consisting of silicatees of sdium and calcium is formed. On cooling . Liquid become viscous and eventually ceasesto flow . It becomes solid and is known as flass. By varying the proportions of the three basic ingredients and by adding other substances, the properties of glass can be altered, Glass can be represented as R_2 O. MO.6SiO_2 , where R= Na or K, M = CaBa, Zn or pbSiO_2 may be replaced by Akl_2 O_3 , b_2 O_3 or P_2 O_5 . Colourd glasses are obtained by adding certain metallic oxdes or salts in the fused mass, Glass is attached by HF and this property is used to make marking on the galss , This is known as etching . The glass on rapid coolling becomes brittle and fragile . The artciles of glass are cooled neither slowly nor very rapidly . The process of graducal cooling of flass iscalled annealing . A special type of glass which contains cerium oxide and does not allow the passage of ultraviolet rays is called .

Read the following paragraph and answer the questions given below , Stable equilibrium is of various types . Mechanical equilibrium is achieved when all particles are at rest and total potential energy of the system is minimum . At any stage where particles are at rest but the system is not at stable equilibrium as it can reduce its potential energy by reverting to another position, is called metastable equilibrium . Thermal equilibrium is result from the absence of temperature gradients in the system. Chemical equilibrium is obtained when no further reaction occurs between reacting substances, i.e forward and reverse rates of reaction are equal. when steam with solid iron at high temperature Fe_3O_4(s) and hydrogen gas are produced . But the reaction never goes to completion. this is because as the products are formed the reaction proceeds in reverse direction and when rate of reverse reaction is equal to rate of forward reaction , the concentration of reactants and products become constant and equilibrium is reached. When a matchbox is balanced on its edge, it is unstable and will tumble to a more stable position resting on its face so as to acquire minimum potential energy. This is an example of

When dilute ferrous sulphate solution is added lto an aqueous solution containing nitrate ion followed by careful addition of concentrated sulphuric acid along the sides of test tube a ,brown ring is formed at the iterface between the solution and sulphuric acid layers .Which is anion is confined by the appearance of brown ring .What the conposition of the brown ring ?

In HCP or CCP constituent particles occupy 74% of the available space. The remaining space (26%) in between the spheres remains unoccupied and is called interstitial voids or holes. Considering the close packing arrangement, each sphere in the second layer rests on the hollow space of the first layer, touching each other. The void created is called tetrahedral void. If R is the radius of the spheres in the close packed arrangement then, R (radius of tetrahedral void) = 0.225 R In a close packing arrangement, the interstitial void formed by the combination of two triangular voids of the first and second layer is called octahedral coid. Thus, double triangular void is surrounded by six spheres. The centre of these spheres on joining, forms octahedron. If R is the radius of the sphere. in a close packed arrangement then, R (radius of octahedral void = 0.414 R). If the anions (A) form hexagonal close packing and cations (C ) occupy only 2/3rd octahedral voids in it, then the general formula of the compound is

TRUEMEN BIOLOGY ENGLISH-Animal Kingdom -ASSERTION AND REASON
  1. [A] : Annelids , Arthropods and mollusks are protostomial coelomates ....

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  2. [A] : The body cavity of earthworm is a true coelem . [R] : It is li...

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  3. [A] : Pearl is formed when a foreign particle gets in between shell an...

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  4. [A] : Fasciola is hermaphrodite . [R] : Gonads are well developed an...

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  5. [A] : There are 10 tidemanns bodies in ambulacral system of echinoderm...

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  6. [A] : Termites and ants are social insects . [R] : They make fungus ...

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  7. Assertion(A): In sponges, archaeocytes are totipotent. Reason( R): T...

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  8. [A] : The honey is a vital food for animals including man . [R] : Th...

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  9. [A] : Leeches secrete hirudin from their salivary glands . [R] : Hir...

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  10. [A] : All invertebrates can keep their body temperature constant all t...

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  11. [A] : In Taenia solium , bladder worm is also known as cysticercus . ...

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  12. [A] : Earthworm obtain oxygen for respiration through moist skin . The...

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  13. [A] : Presence of alimentary canal would not have suited the mode of l...

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  14. [A]: Development in cockroach is termed as retrogressive metamorphosis...

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  15. [A] : All the gills of Palaemon are phyllobranchs . [R] : Each gill ...

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  16. [A] : Renal-sac of Prawn functions in same manner as vertebrate kidney...

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  17. [A] : Pila is adopted to lead an amphibious life . [R] : It is provi...

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  18. [A] : Chordates have poor regeneration power while non-chordates have ...

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  19. [A] : In lower invertebrates the digestion is intracellular while in h...

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  20. [A] : Chordates have an oxygen carrying pigment called haemoglobin . I...

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