In the given figure, O is the centre of two concentric circles of radii 4 cm and 6 cm respectively.
Question: In the given figure,Ois the centre of two concentric circles of radii 4 cm and 6 cm respectively.PAandPBare tangents to the outer and inner circles, respectively. IfPA= 10 cm, find the length ofPBup to one decimal place. Solution: Given, $O$ is the centre of two concentric circles of radii $O A=6 \mathrm{~cm}$ and $O B=4 \mathrm{~cm}$. $P A$ and $P B$ are the two tangents to the outer and inner circles respectively and $P A=10 \mathrm{~cm}$. Now, tangent drawn from an external point is...
Read More →What is the basic structural difference between starch and cellulose?
Question: What is the basic structural difference between starch and cellulose? Solution: Starch consists of two components amylose and amylopectin. Amylose is a long linear chain ofD(+)glucose units joined by C1C4 glycosidic linkage (-link). Amylopectin is a branched-chain polymer of-D-glucose units, in which the chain is formed by C1C4 glycosidic linkage and the branching occurs by C1C6 glycosidic linkage. On the other hand, cellulose is a straight-chain polysaccharide of-D-glucose units joine...
Read More →Initially a gas of diatomic molecules is contained in a cylinder
Question: Initially a gas of diatomic molecules is contained in a cylinder of volume $V_{1}$ at a pressure $P_{1}$ and temperature $250 \mathrm{~K}$. Assuming that $25 \%$ of the molecules get dissociated causing a change in number of moles. The pressure of the resulting gas at temperature $2000 \mathrm{~K}$, when contained in a volume $2 V_{1}$ is given by $P_{2}$. The ratio $P_{2} / P_{1}$ is_______ Solution: (5) Using ideal gas equation, $P V=n R T$ $\Rightarrow P_{1} V_{1}=n R \times 250 \qu...
Read More →Find the volume of a solid in the form of a right circular
Question: Find the volume of a solid in the form of a right circular cylinder with hemi-spherical ends whose total length is 2.7 m and the diameter of each hemi-spherical end is 0.7 m. Solution: Radius of hemispherical ends = radius of cylinder $=\frac{1}{2} \times 0.7$ $=\frac{7}{20} \mathrm{~m}$ Total length = 2.7 m. Height of cylinder $=2.7-2 \times \frac{7}{20}$ $=2 \mathrm{~m}$ Volume of two hemispheres $=2\left(\frac{2}{3} \pi r^{3}\right)$ $=\frac{4}{3} \pi r^{3}$ $=\frac{4}{3} \times \fr...
Read More →What are the hydrolysis products of
Question: What are the hydrolysis products of(i)sucrose and(ii)lactose? Solution: (i)On hydrolysis, sucrose gives one molecule of-D glucose and one molecule of- D-fructose. (ii)The hydrolysis of lactose gives-D-galactose and-D-glucose....
Read More →In the given figure, an isosceles triangle ABC with AB = AC, circumscribes a circle.
Question: In the given figure, an isosceles triangle ABC with AB = AC, circumscribes a circle. Prove that the point of contact P bisects the base BC Solution: We know that tangent segments to a circle from the same external point are congruent.Now, we haveAR = AQ, BR = BP and CP = CQNow, AB = AC⇒ AR + RB = AQ + QC⇒ AR + RB = AR + QC⇒ RB = QC⇒ BP = CPHence, P bisects BC at P....
Read More →What is glycogen?
Question: What is glycogen? How is it different from starch? Solution: Glycogen is a carbohydrate(polysaccharide). In animals, carbohydrates are stored as glycogen. Starch is a carbohydrate consisting of two components amylose (15 20%) and amylopectin (80 85%). However,glycogen consists of only one component whose structure is similar to amylopectin. Also, glycogen is more branched than amylopectin....
Read More →In the given figure, a circle touches all the four sides of a quadrilateral ABCD whose three sides are AB = 6 cm,
Question: In the given figure, a circle touches all the four sides of a quadrilateralABCDwhose three sides areAB= 6 cm,BC= 7 cm andCD= 4 cm. FindAD. Solution: Let the circle touch the sides of the quadrilateral $A B, B C, C D$ and $D A$ at $P, Q, R$ and $S$ respectively. Given, $A B=6 \mathrm{~cm}, B C=7 \mathrm{~cm}$ and $C D=4 \mathrm{~cm}$. Tangents drawn from an external point are equal. $\therefore A P=A S, B P=B Q, C R=C Q$ and $D R=D S$ Now, $A B+C D=(A P+B P)+(C R+D R)$ $=A B+C D=(A S+B ...
Read More →In an adiabatic process, the density of a diatomic gas becomes 32 times its initial value.
Question: In an adiabatic process, the density of a diatomic gas becomes 32 times its initial value. The final pressure of the gas is found to be $n$ times the initial pressure. The value of $n$ is:32326128$\frac{1}{32}$Correct Option: , 3 Solution: (3) In adiabatic process $P V^{\gamma}=$ constant $\therefore P\left(\frac{m}{\rho}\right)^{\gamma}=$ constant $\left(\because V=\frac{m}{\rho}\right)$ As mass is constant $\therefore P \propto \rho^{\gamma}$ If $P_{i}$ and $P_{f}$ be the initial and...
Read More →What do you understand by the term glycosidic linkage?
Question: What do you understand by the term glycosidic linkage? Solution: Glycosidic linkage refers to the linkage formedbetween two monosaccharide units through an oxygen atom by the loss of a water molecule. For example, in a sucrose molecule, two monosaccharide units,-glucose and-fructose, are joined together by a glycosidic linkage....
Read More →Classify the following into monosaccharides and disaccharides.
Question: Classify the following into monosaccharides and disaccharides. Ribose, 2-deoxyribose, maltose, galactose, fructose and lactose Solution: Monosaccharides: Ribose, 2-deoxyribose, galactose, fructose Disaccharides: Maltose, lactose...
Read More →A cylindrical container is filled with ice-cream,
Question: A cylindrical container is filled with ice-cream, whose diameter is 12 cm and height is 15 cm. the whole ice-cream is distributed to 10 children in equal cones having hemispherical tops. If the height of the conical portion is twice the diameter of its base, find the diameter of the ice-cream. Solution: Volume of cylindrical container $=\pi r^{2} h$ $=\pi \times(6)^{2} \times 15$ Amount of ice-cream distributed to 10 children $=\frac{\pi \times(6)^{2} \times 15}{10}$ Therefore, Height ...
Read More →Write two main functions of carbohydrates in plants.
Question: Write two main functions of carbohydrates in plants. Solution: Two main functions of carbohydrates in plants are: (i)Polysaccharides such as starch serve as storage molecules. (ii)Cellulose, a polysaccharide, is used to build the cell wall....
Read More →A circle is inscribed in ΔABC, touching AB, BC and AC at P, Q and R, respectively.
Question: A circle is inscribed in ΔABC,touchingAB, BCandACatP,QandR, respectively. IfAB= 10 cm,AR= 7 cm andCR= 5 cm, find the length ofBC. Solution: Given, a circle inscribed in triangle $\mathrm{ABC}$, such that the circle touches the sides of the triangle at $\mathrm{P}, \mathrm{Q}, \mathrm{R}$. Tangents drawn to a circle from an external point are equal. $\therefore \mathrm{AP}=\mathrm{AR}=7 \mathrm{~cm}, \mathrm{CQ}=\mathrm{CR}=5 \mathrm{~cm} .$ Now, $B P=(A B-A P)=(10-7)=3 \mathrm{~cm}$ $\...
Read More →What are reducing sugars?
Question: What are reducing sugars? Solution: Reducing sugars are carbohydratesthat reduce Fehlings solution and Tollens reagent. All monosaccharides and disaccharides, excluding sucrose, are reducing sugars....
Read More →What are monosaccharides?
Question: What are monosaccharides? Solution: Monosaccharides are carbohydrates that cannot be hydrolysed further to give simpler units of polyhydroxy aldehyde or ketone. Monosaccharides are classified on the bases of number of carbon atoms and the functional group present in them. Monosaccharides containing an aldehyde group are known as aldoses and those containing a keto group are known as ketoses. Monosaccharides are further classified as trioses, tetroses, pentoses, hexoses, and heptoses ac...
Read More →A toy is in the form of a cone mounted on a hemisphere
Question: A toy is in the form of a cone mounted on a hemisphere of radius 3.5 cm. The total height of the toy is 15.5 cm find the total surface area and volume of the toy. Solution: Radius of hemisphere = 3.5 cm Total height of the toy = 15.5 cm. Surface area of cone $=\pi r l$ $I=\sqrt{(12)^{2}+(3.5)^{2}}$ $=\sqrt{156.25}$ $=12.5 \mathrm{~cm}$ Therefore, Surface area of cone $=\frac{22}{7} \times 3.5 \times 12.5$ $=137.5 \mathrm{~cm}^{2}$ Surface area of hemisphere $=2 \pi r^{2}$ $=77 \mathrm{...
Read More →When RNA is hydrolysed,
Question: When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA? Solution: A DNA molecule is double-stranded in which the pairing of bases occurs. Adenine always pairs with thymine, while cytosine always pairs with guanine. Therefore, on hydrolysis of DNA, the quantity of adenine produced is equal to that of thymine and similarly, the quantity of cytosine is equal to that of guanine. But when RNA ...
Read More →Three different processes that can occur in an ideal monoatomic gas
Question: Three different processes that can occur in an ideal monoatomic gas are shown in the $\mathrm{P}$ vs $\mathrm{V}$ diagram. The paths are lebelled as $\mathrm{A} \rightarrow \mathrm{B}, \mathrm{A} \rightarrow \mathrm{C}$ and $\mathrm{A} \rightarrow \mathrm{D}$. The change in internal energies during these process are taken as $E_{A B}$, $E_{\mathrm{AC}}$ and $E_{\mathrm{AD}}$ and the workdone as $W_{\mathrm{AB}}, W_{\mathrm{AC}}$ and $W_{\mathrm{AD}}$. The correct relation between these...
Read More →What products would be formed when a nucleotide from DNA
Question: What products would be formed when a nucleotide from DNA containing thymine is hydrolysed? Solution: When a nucleotide from the DNA containing thymine is hydrolyzed, thymine -D-2-deoxyribose and phosphoric acid are obtained as products....
Read More →From an external point P, tangents PA and PB are drawn to a circle with centre O.
Question: From an external pointP,tangentsPAandPBare drawn to a circle with centreO. IfCDis the tangent to the circle at a pointEandPA= 14 cm, find the perimeter of ΔPCD. Solution: Given, $\mathrm{PA}$ and $\mathrm{PB}$ are the tangents to a circle with centre $\mathrm{O}$ and $\mathrm{CD}$ is a tangent at $\mathrm{E}$ and $\mathrm{PA}=14 \mathrm{~cm} .$ Tangents drawn from an external point are equal. $\therefore P A=P B, C A=C E$ and $D B=D E$ Perimeter of $\triangle P C D=P C+C D+P D$ $=(P A-...
Read More →Why cannot vitamin C be stored in our body?
Question: Why cannot vitamin C be stored in our body? Solution: Vitamin C cannot be stored in our body because it is water soluble. As a result, it is readily excreted in the urine....
Read More →Where does the water present in the egg go after boiling the egg?
Question: Where does the water present in the egg go after boiling the egg? Solution: When an egg is boiled, the proteins present inside the egg get denatured and coagulate. After boiling the egg, the water present in it is absorbed by the coagulated protein through H-bonding....
Read More →A tent is in the form of a right circular cylinder surmounted by a cone.
Question: A tent is in the form of a right circular cylinder surmounted by a cone. The diameter of the base of the cylinder or the cone is 24 m. The height of the cylinder is 11 m. If the vertex of the cone is 16 m above the ground, find the area of the canvas required for making the tent.(Use = 22/7) Solution: Surface area of cylindrical part $=2 \pi r h$ $=2 \times \frac{22}{7} \times \frac{24}{2} \times 11$ $=829.71 \mathrm{~m}^{2}$ Height of cone $=16-11$ $=5 \mathrm{~m} .$ Surface area of c...
Read More →The melting points and solubility in water of amino acids are generally higher than that of the corresponding halo acids.
Question: The melting points and solubility in water of amino acids are generally higher than that of the corresponding halo acids. Explain. Solution: Both acidic (carboxyl) as well as basic (amino) groups are present in the same molecule of amino acids. In aqueous solutions, the carboxyl group can lose a proton and the amino group can accept a proton, thus giving rise to a dipolar ion known as a zwitter ion. Due to this dipolar behaviour, they have strong electrostatic interactions within them ...
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