eSaral - JEE | NEET | Class 8-10 Exam Prep App

Arrange the compounds of each set in order of

Question: Arrange the compounds of each set in order of reactivity towards SN2 displacement: (i)2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane (ii)1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 3-Bromo-2- methylbutane (iii)1-Bromobutane, 1-Bromo-2,2-dimethylpropane, 1-Bromo-2-methylbutane, 1-Bromo-3-methylbutane. Solution: (i) An SN2reaction involves the approaching of the nucleophile to the carbon atom to which the leaving group is attached. When the nucleophile is sterically hindered,...

The circuit shown below is working as a 8 V dc regulated voltage source.

Question: The circuit shown below is working as a $8 \mathrm{~V}$ dc regulated voltage source. When $12 \mathrm{~V}$ is used as input, the power dissipated (in $\mathrm{mW}$ ) in each diode is; (considering both zener diodes are identical)___________ Solution: (40) Current in the circuit, $I=\frac{12-8}{400}=10^{-2} \mathrm{~A}$ Power dissipited in each diode, $P=V I$ $\Rightarrow P=4 \times 10^{-2}=40 \mathrm{~mW}$...

The perimeters of the ends of a frustum of a right circular

Question: The perimeters of the ends of a frustum of a right circular cone are 44 cm and 33 cm. If the height of the frustum be 16 cm, find its volume, the slant surface and the total surface. Solution: The height of the frustum of the cone ish= 16 cm. The perimeters of the circular ends are 44 cm and 33 cm. Let the radii of the bottom and top circles arer1cm andr2cm respectively. Then, we have $2 \pi r_{1}=44$ $\Rightarrow \pi r_{1}=22$ $\Rightarrow \quad r_{1}=\frac{22 \times 7}{22}$ $\Rightar...

Write the mechanism of the following reaction:

Question: Write the mechanism of the following reaction: Solution: The given reaction is: The given reaction is an SN2 reaction. In this reaction, CNacts as the nucleophile and attacks the carbon atom to which Br is attached. CNion is an ambident nucleophile and can attack through both C and N. In this case, it attacks through the C-atom....

It is given that ∆ABC ∼ ∆DEF. If ∠A = 30°, ∠C = 50°, AB = 5 cm, AC = 8 cm and DF = 7.5 cm

Question: It is given that ∆ABC ∆DEF. If A= 30, C= 50,AB= 5 cm,AC= 8 cm andDF= 7.5 cm, then which of the following is true?(a)DE= 12 cm, F= 50(b)DE= 12 cm, F= 100(c)EF= 12 cm, D= 100(d)EF= 12 cm, F= 30 Solution: (b) $D E=12 \mathrm{~cm}, \angle F=100^{\circ}$ Disclaimer:In the question, it should be ∆ABC ∆DFEinstead of ∆ABC ∆DEF.In triangle ABC, $\angle A+\angle B+\angle C=180^{\circ}$ $\therefore \angle B=180-30-50=100^{\circ}$ ∵∆ABC ∆DFE $\therefore \angle D=\angle A=30^{\circ}$ $\angle F=\ang...

Write the structure of the major organic product in each of the following reactions:

Question: Write the structure of the major organic product in each of the following reactions: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) Solution: (ii) (viii)...

Both the diodes used in the circuit shown are assumed to be ideal

Question: Both the diodes used in the circuit shown are assumed to be ideal and have negligible resistance when these are forward biased. Built in potential in each diode is $0.7 \mathrm{~V}$. For the input voltages shown in the figure, the voltage (in Volts) at point $\mathrm{A}$ is________ Solution: (12) Right hand diode is reversed biased and left hand diode is forward biased. Hence Voltage at 'A' $V_{A}=12.7-0.7=12 \mathrm{volt}$...

The slant height of the frustum of a cone is 4 cm

Question: The slant height of the frustum of a cone is 4 cm and the perimeters of its circular ends are 18 cm and 6 cm. Find the curved surface of the frustum. Solution: The slant height of the frustum of the cone isl= 4 cm. The perimeters of the circular ends are 18 cm and 6 cm. Let the radii of the bottom and top circles arer1cm andr2cm respectively. Then, we have $2 \pi r_{1}=18$ $\Rightarrow \pi r_{1}=9$ $2 \pi r_{2}=6$ $\Rightarrow \pi r_{2}=3$ The curved surface area of the frustum cone is...

Give the uses of freon 12, DDT,

Question: Give the uses of freon 12, DDT, carbon tetrachloride and iodoform. Solution: Uses of Freon 12 Freon-12 (dichlorodifluoromethane, CF2Cl2) is commonly known as CFC. It is used as a refrigerant in refrigerators and air conditioners. It is also used in aerosol spray propellants such as body sprays, hair sprays, etc. However, it damages the ozone layer. Hence, its manufacture was banned in the United States and many other countries in 1994. Uses of DDT DDT (p, pdichlorodiphenyltrichloroetha...

Explain why

Question: Explain why (i)the dipole moment of chlorobenzene is lower than that of cyclohexyl chloride? (ii)alkyl halides, though polar, are immiscible with water? (iii)Grignard reagents should be prepared under anhydrous conditions? Solution: (i) In chlorobenzene, the Cl-atom is linked to asp2hybridized carbon atom. In cyclohexyl chloride, the Cl-atom is linked to asp3hybridized carbon atom. Now,sp2hybridized carbon has more s-character thansp3hybridized carbon atom. Therefore, the former is mor...

A frustum of a right circular cone has a diameter of base 20 cm,

Question: A frustum of a right circular cone has a diameter of base 20 cm, of top 12 cm, and height 3 cm. Find the area of its whole surface and volume. Solution: The radii of the bottom and top circles arer1=10 cm andr2= 6 cm respectively. The height of the frustum cone ish= 3 cm. Therefore, the volume of the bucket is $V=\frac{1}{3} \pi\left(r_{1}^{2}+r_{1} r_{2}+r_{2}^{2}\right) \times h$ $=\frac{1}{3} \pi\left(10^{2}+10 \times 6+6^{2}\right) \times 3$ $=\frac{1}{3} \times \frac{22}{7} \times...

ABC and BDE are two equilateral triangles such that D is the mid point of BC.

Question: ABC and BDE are two equilateral triangles such that D is the mid point of BC. Ratio of the areas of triangles ABC and BDE is(a) 1 : 2(b) 2 : 1(c) 1 : 4(d) 4 : 1 Solution: Given: ABC and BDE are two equilateral trianglesSince, D is the mid point of BC and BDE is also an equilateral traingle.Hence, E is also the mid point of AB.Now, D and E are the mid points of BC and AB.In a triangle, the line segment that joins the midpoints of the two sides of a triangle is parallel to the third side...

In the given circuit, value of Y is:

Question: In the given circuit, value of $Y$ is: 0toggles between 0 and 1will not execute1Correct Option: 1 Solution: $Y=\overline{\overline{A B} \cdot A}=\overline{\overline{A B}}+\bar{A}=A B+\bar{A}$ For $A=1, B=0$ $Y=(1) \times 0+0$ $\Rightarrow Y=0+0=0$...

How will you bring about the following conversions?

Question: How will you bring about the following conversions? (i)Ethanol to but-1-yne (ii)Ethane to bromoethene (iii)Propene to 1-nitropropane (iv)Toluene to benzyl alcohol (v)Propene to propyne (vi)Ethanol to ethyl fluoride (vii)Bromomethane to propanone (viii)But-1-ene to but-2-ene (ix)1-Chlorobutane to n-octane (x)Benzene to biphenyl. Solution: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x)...

A bucket has top and bottom diameter of 40 cm and 20 cm respectively.

Question: A bucket has top and bottom diameter of 40 cm and 20 cm respectively. Find the volume of the bucket if its depth is 12 cm. Also, find the cost of tin sheet used for making the bucket at the rate of Rs. 1.20 per dm2. (Use = 3.14) Solution: The radii of the top and bottom circles arer1=20 cm andr2= 10 cm respectively. The height of the bucket ish= 12 cm. Therefore, the volume of the bucket is $V=\frac{1}{3} \pi\left(r_{1}^{2}+r_{1} r_{2}+r_{2}^{2}\right) \times h$ $=\frac{1}{3} \pi\left(...

In ∆ABC, it is given that AB = 9 cm, BC = 6 cm and CA = 7.5 cm.

Question: In ∆ABC,it is given thatAB= 9 cm,BC= 6 cm andCA= 7.5 cm. Also, in ∆DEF,EF= 8 cm and ∆DEF ∆ABC. Then, perimeter of ∆DEFis(a) 22.5 cm(b) 25 cm(c) 27 cm(d) 30 cm Solution: (d) 30 cm Perimeter of $\triangle A B C=A B+B C+C A=9+6+7.5=22.5 \mathrm{~cm}$ $\because \triangle D E F \sim \triangle A B C$ $\therefore \frac{\text { Perimeter } \triangle(A B C)}{\text { Perimeter }(\triangle D E F)}=\frac{B C}{E F}$ $\Rightarrow \frac{22.5}{\text { Perimeter }(\triangle D E F)}=\frac{6}{8}$ $\Right...

Predict all the alkenes that would be formed by dehydrohalogenation of the following

Question: Predict all the alkenes that would be formed by dehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene: (i)1-Bromo-1-methylcyclohexane (ii)2-Chloro-2-methylbutane (iii)2,2,3-Trimethyl-3-bromopentane. Solution: (i) In the given compound, there are two types of-hydrogen atoms are present. Thus, dehydrohalogenation of this compound gives twoalkenes. (ii) In the given compound, there are two different sets of equivalent -hydrogen atoms ...

∆ABC ∼ ∆DEF such that AB = 9.1 cm and DE = 6.5 cm.

Question: ∆ABC ∆DEFsuch thatAB= 9.1 cm andDE= 6.5 cm. If the perimeter of ∆DEFis 25 cm, what is the perimeter of ∆ABC?(a) 35 cm(b) 28 cm(c) 42 cm(d) 40 cm Solution: (a) 35 cm∵∆ABC ∆DEF $\therefore \frac{\text { Perimeter }(\triangle A B C)}{\text { Perimeter }(\triangle D E F)}=\frac{A B}{D E}$ $\Rightarrow \frac{\text { Perimeter }(\triangle A B C)}{25}=\frac{9.1}{6.5}$ $\Rightarrow$ P erimeter $(\triangle A B C)=\frac{9.1 \times 25}{6.5}=35 \mathrm{~cm}$...

Boolean relation at the output stage- Y for the following circuit is:c

Question: Boolean relation at the output stage- $Y$ for the following circuit is: $\bar{A}+\bar{B}$$A+B$$A . B$$\bar{A} \cdot \bar{B}$Correct Option: , 4 Solution: $\mathrm{OR}+\mathrm{NOT} \rightarrow \mathrm{NOR}$ Gate Hence Boolean relation at the output stage $-Y$ for the circuit, $Y=\overline{A+B}=\bar{A} \cdot \bar{B}$...

A toy is in the form of a hemisphere surmounted by a right circular

Question: A toy is in the form of a hemisphere surmounted by a right circular cone of the same base radius as that of the hemisphere. If the radius of the base of the cone is 21 cm and its volume is 2/3 of the volume of hemisphere, calculate the height of the cone and the surface area of the toy. (Use $\pi=22 / 7$ ). Solution: Let the height of the conical part beh. Radius of the cone = Radius of the hemisphere =r= 21 cm The toy can be diagrammatically represented as Volume of the cone $=\frac{1...

∆ABC ∼ ∆DEF and the perimeters of ∆ABC and ∆DEF are 30 cm and 18 cm respectively.

Question: ∆ABC ∆DEFand the perimeters of ∆ABCand ∆DEFare 30 cm and 18 cm respectively. IfBC= 9 cm, thenEF= ?(a) 6.3 cm(b) 5.4 cm(c) 7.2 cm(d) 4.5 cm Solution: (b) 5.4 cm∆ABC ∆DEFTherefore, $\frac{\text { Perimeter }(\triangle A B C)}{\text { Perimeter }(\triangle D E F)}=\frac{B C}{E F}$ $\Rightarrow \frac{30}{18}=\frac{9}{E F}$. $\Rightarrow E F=\frac{9 \times 18}{30}=5.4 \mathrm{~cm}$...

Solve this

Question: In $\Delta A B C, D E \| B C$ such that $\frac{A D}{D B}=\frac{3}{5}$. IfAC= 5.6 cm, thenAE= ? (a) 4.2 cm(b) 3.1 cm(c) 2.8 cm(d) 2.1 cm Solution: (d) 2.1 cm It is given that $\mathrm{DE} \| B C$. Applying Thales' theorem, we get: $\frac{A D}{D B}=\frac{A E}{E C}$ Let $A E$ be $x \mathrm{~cm}$. Therefore, $E C=(5.6-x) \mathrm{cm}$ $\Rightarrow \frac{3}{5}=\frac{x}{5.6-x}$ $\Rightarrow 3(5.6-x)=5 x$ $\Rightarrow 16.8-3 x=5 x$ $\Rightarrow 8 x=16.8$ $\Rightarrow x=2.1 \mathrm{~cm}$...

Which compound in each of the following pairs will react faster in

Question: Which compound in each of the following pairs will react faster in SN2 reaction with OH? (i)CH3Br or CH3I (ii)(CH3)3CCl or CH3Cl Solution: (i)In the SN2 mechanism, the reactivity of halides for the same alkyl group increases in the order. This happens because as the size increases, the halide ion becomes a better leaving group. RF RCl RBr RI Therefore, CH3I will react faster than CH3Br in SN2 reactions with OH. (ii) The SN2 mechanism involves the attack of the nucleophile at the atom b...

A hemispherical depression is cut out from

Question: A hemispherical depression is cut out from one face of a cubical wooden block of edge 21 cm, such that the diameter of the hemisphere is equal to the edge of the cube. Determine the volume and total surface area of the remaining block. Solution: We have to find the remaining volume and surface area of a cubical box when a hemisphere is cut out from it. Edge length of cube $(a)=21 \mathrm{~cm}$ Radius of hemisphere $(r)=10.5 \mathrm{~cm}$ Therefore volume of the remaining block, $=$ Vol...

What are ambident nucleophiles?

Question: What are ambident nucleophiles? Explain with an example. Solution: Ambident nucleophiles are nucleophiles having two nucleophilic sites. Thus, ambident nucleophiles have two sites through which they can attack. For example, nitrite ion is an ambident nucleophile. Nitrite ion can attack through oxygen resulting in the formation of alkyl nitrites. Also, it can attack through nitrogen resulting in the formation of nitroalkanes....

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