Recent questions tagged class12

$8.0575\times 10^{-2}Kg$ of Glauber's salt is dissolved in water to obtain $1dm^3$ of a solution of density 1077.2$Kgm^{-3}$.Calculate the molarity ,molality and mole fraction of $Na_2SO_4$ in solution.

asked Jan 7, 2014 by sreemathi.v

1 answer

If $\overrightarrow a=2\hat i+\hat j-2\hat k\:\;and\:\:\overrightarrow b=\hat i+\hat j$ and $\overrightarrow c$ is such that $\overrightarrow c.\overrightarrow a=|\overrightarrow c|$, $|\overrightarrow c-\overrightarrow a|=2\sqrt 2$ and the angle between $\overrightarrow a\times\overrightarrow b$ and $\overrightarrow c$ is $30^{\circ}$, then $|(\overrightarrow a\times\overrightarrow b)\times\overrightarrow c|=?$

asked Jan 7, 2014 by rvidyagovindarajan_1

1 answer

If $\overrightarrow a,\overrightarrow b$ are mutually $\perp$ unit vectors and the vectors $x\overrightarrow a+x\overrightarrow b+z(\overrightarrow a\times\overrightarrow b ),\:\:\overrightarrow a+(\overrightarrow a\times\overrightarrow b),\:\:and\:\:z\overrightarrow a+z\overrightarrow b+y(\overrightarrow a\times\overrightarrow b)$ lie in a plane then $Z$ is ?

asked Jan 6, 2014 by rvidyagovindarajan_1

1 answer

If $E_e$ be the electric field strength of a short dipole at a point on the equitorial line and $ E_a$ be that on axial line at same distance then :

asked Jan 6, 2014 by meena.p

1 answer

16 dipoles of charge of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be :

asked Jan 6, 2014 by meena.p

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An alpha particle is accelerated by a potential difference of $10^7 V$. Its kinetic energy will be

asked Jan 6, 2014 by meena.p

1 answer

A $20 \mu F$ capacitor and $ 40 \; \mu F$ capacitor are connected in series across $400\; V$ supply line. The charged capacitors are then disconnected from the line and reconnected with their positive plates together and negative plates together. No external voltage is applied. What is potential difference across each capacitor .

asked Jan 6, 2014 by meena.p

1 answer

If $\overrightarrow a,\overrightarrow b,\overrightarrow c$ are unit vectors and $\overrightarrow a+\overrightarrow b+\overrightarrow c$ is also a unit vector and $\alpha,\beta,\gamma $ are angles between $\overrightarrow a\:and\:\overrightarrow b,\:\:\overrightarrow b\:and\:\overrightarrow c\:\:\overrightarrow c\:and\:\overrightarrow a$ respectively, then among the three angles,

asked Jan 6, 2014 by rvidyagovindarajan_1

1 answer

If $\overrightarrow a,\overrightarrow b,\overrightarrow c$ are any three vectors such that $\overrightarrow a=\overrightarrow b+\overrightarrow c$ and $\overrightarrow b$ is $\perp$ to $\overrightarrow c$, then ?

asked Jan 6, 2014 by rvidyagovindarajan_1

1 answer

For a poisson variate X if $P(X=0) = 0.2$ then its variance is

asked Jan 6, 2014 by thanvigandhi_1

1 answer

A dielectric slab is introduced just to fill up the space between plates of parallel plate capacitor. The capacitor is charged and then disconnected . The slab is then slowly drown out . The plot of potential difference across the plates and length of dielectric slab drawn out looks like :

asked Jan 6, 2014 by meena.p

1 answer

The value of $k$ for which the line $\large\frac{x-4}{1}=\frac{y-2}{1}=\frac{z-k}{2}$ to lie on the plane $2x-4y+3z=6$ is ?

asked Jan 6, 2014 by rvidyagovindarajan_1

1 answer

Choose incorrect statement : When two identical capacitors are charged individually to different potential, and connected to each other after disconnecting them from source .

asked Jan 6, 2014 by meena.p

1 answer

If $ E_1$ denotes the event of coming sum 6 in throwing two dice and $E_2$ be the event of coming 2 in any one of the two, then $ P(E_2/E_1)$ is

asked Jan 6, 2014 by thanvigandhi_1

1 answer

An uncharged capacitor is connected to a battery. On charging the capacitor :

asked Jan 6, 2014 by meena.p

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A capacitor is charged to $3200 V$ and then connected across a resistor of resistance R. If after 1 s potential difference across capacitor is 2400 V, What will be the potential difference across after 2 and 3 seconds .

asked Jan 6, 2014 by meena.p

1 answer

1. The theca layer of ovarian follicles is organised into an inner theca interna and an outer theca externa. 2. The primary oocyte within the tertiary follicle grows in size and completes its first meiotic division. 3. First meiotic division is an unequal division resulting in the formation of a large haploid tertiary oocyte and a tiny first polar body Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Each primary oocyte then gets surrounded by a layer of granulosa cells and is called the primary follicle. 2. The primary follicles get surrounded by more layers of granulosa cells and a new theca and are called secondary follicles. 3. The secondary follicle soon transforms into a tertiary follicle which is characterised by a fluid filled cavity called antrum. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Oogonia start division and enter into prophase-II of the meiotic division 2. Oogonia get temporarily arrested at that stage are called primary oocytes. 3. Each primary oocyte then gets surrounded by a layer of granulosa cells and is called the primary follicle. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. The process of formation of a mature female gamete is called oogenesis. 2. Oogenesis is initiated during puberty when a couple of million gamete mother cells (oogonia) are formed within each mature ovary. 3. More oogonia are formed and added during 18 to 35 years (reproductive period). Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Sperms released from the seminiferous tubules, are transported by the accessory ducts. 2. Secretions of epididymis, vas deferens, seminal vesicle and prostate are essential for maturation of sperms. 3. Secretions of epididymis, vas deferens, seminal vesicle and prostate are essential for motility of sperms. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

The human male ejaculates (i) about 20 to 30 million sperms during a coitus of which, (ii) for normal fertility, at least 40 per cent sperms must have normal shape and size and (iii) for normal fertility, at least 50 per cent of them must show vigorous motility. Regarding (i), (ii) and (iii) :

asked Jan 6, 2014 by pady_1

1 answer

1. A plasma membrane envelops the whole body of sperm. 2. The sperm head contains an elongated haploid nucleus. 3. The posterior portion of nucleus is covered by a cap-like structure, acrosome. 4. The acrosome is filled with enzymes that help fertilisation of the ovum. Regarding 1,2,3 and 4 :

asked Jan 6, 2014 by pady_1

1 answer

1. The spermatids are transformed into spermatozoa by the process called gametogenesis. 2. After spermiogenesis, sperm heads become embedded in the Leydig cells. 3. And they are finally released from the seminiferous tubules by the process called spermiation. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Primary spermatocytes periodically undergo meiosis. 2. A primary spermatocyte completes the first meiotic division leading to formation of four secondary spermatocytes. 3. Secondary spermatocytes undergo the second meiotic division to produce four unequal, haploid spermatids. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Each spermatogonium contains 46 chromosomes. 2. Primary spermatocytes have 23 chromosomes each. 3. Secondary spermatocytes also have 23 chromosomes each. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

In testis: 1. The immature male germ cells are called spermatogonia (sing. spermatogonium). 2. Spermatogonia produce sperms by spermatogenesis. 3. Spermatogenesis begins at puberty. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. The alveoli open into mammary tubules. 2. The tubules of each lobe join to form a lactiferous duct. 3. Several lactiferous ducts join to form a wider mammary ampulla 4. Mammary ampulla is connected to mammary duct. Regarding 1,2,3 and 4 :

asked Jan 6, 2014 by pady_1

1 answer

1. The glandular tissue of each breast is divided into 5-10 mammary lobes containing clusters of cells called alveoli. 2. The cells of alveoli secrete milk. 3. Milk is stored in the cavities (lumens) of alveoli. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Mons pubis is a cushion of fatty tissue covered by skin and pubic hair. 2. The *** minora are fleshy folds of tissue, which extend down from the mons pubis and surround the vaginal opening. 3. The * majora are paired folds of tissue under the *** minora. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. The uterus opens into ****** through a broad cervix. 2. The cavity of the cervix is called cervical canal. 3. Cervical canal solely forms the birth canal. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. The infundibulum leads to a wider part of the oviduct called isthmus. 2. The last part of the oviduct is ampulla. 3. Ampulla has a narrow lumen. 4. Isthmus joins the uterus. Regarding 1,2,3 and 4 :

asked Jan 6, 2014 by pady_1

1 answer

1. The ovaries are located one on each side of the upper abdomen. 2. Each ovary is about 2 to 4 cm in length 3. They are connected to the pelvic wall and uterus by ligaments. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

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1. The *** is the male external genitalia 2. It is made up of special tissue that helps in erection of the * 3. Erection of the *** facilitates insemination. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

2 answers

1. The urethra originates from the urinary bladder 2. It extends through the ***** to its external opening 3. Its external opening called urethral meatus. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

In testes : 1. Each seminiferous tubule is lined on its inside by two types of cells called male germ cells and Sertoli cells. 2. Sertoli cells undergo meiotic divisions finally leading to sperm formation. 3. The male germ cells provide nutrition to the germ cells. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

The male reproductive system : 1. The testes are situated outside the abdominal cavity within a pouch called . 2. The helps in maintaining the high temperature of the testes, 2–2.5o C higher than the normal internal body temperature. 3. 2–2.5o C higher than the normal internal body temperature is necessary for spermatogenesis. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

In artificial insemination (AI) technique: (i) the semen collected from the husband (ii) the semen collected from a healthy donor (iii) is artificially introduced into the ****** of the female (iv) is artificially introduced into the uterus of the female Regarding (i), (ii), (iii) and (iv) :

asked Jan 6, 2014 by pady_1

1 answer

GIFT: Transfer of an ovum collected from a donor (i) into the fallopian tube of another female (ii) who can produce one (iii) but can not provide suitable environment for fertilisation (iv) but can provide suitable environment for further development Regarding (i), (ii), (iii) and (iv) :

asked Jan 6, 2014 by pady_1

1 answer

ART: 1. The zygote or early embryos (with upto 8 blastomeres) could then be transferred into the fallopian tube(ZIFT) 2. Embryos with more than 8 blastomeres, into the uterus, to complete its further development.(IUT) 3. Embryos formed by in-vivo fertilisation (fusion of gametes within the female) also could be used for such transfer to assist those females who cannot conceive. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

In vitro fertilisation (IVF) : (i) also known as test tube baby programme (ii) ova from the wife/donor (female) and sperms from the husband/donor (male) are collected (iii) they are induced to form zygote (iv) under simulated conditions in the laboratory. Regarding (i), (ii), (iii) and (iv) :

asked Jan 6, 2014 by pady_1

1 answer

Two equal and opposite charges $ 8 \times 10^{-8} C$ are placed $ 2 \times 10^{-2} $ cm away from a dipole . If this dipole is placed in an external electric field $2 \times 10^8 N/C$. the value of maximum torque and work done in rotating through $180^{\circ}$ will be :

asked Jan 6, 2014 by meena.p

1 answer

In ART : 1. In vitro fertilisation (IVF ) is fertilisation outside the body 2. It is done in almost similar conditions as that in the body. 3. IVF is followed by embryo transfer (ET) is one of such methods. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Hepatitis–B and HIV can be transmitted from an infected mother to the foetus too. 2. Hepatitis B virus transmission from mother to unborn child is called vertical transmission. 3. Before semen donation for artificial insemination the screening of donor for HBV is not usually needed Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

1. Hepatitis–B and HIV can be transmitted by sharing of injection needles, razors, etc. 2. HIV can be transmitted by using surgical instruments used on for such patients and used after disinfection. 3. Hepatitis–B and HIV can be transmitted by transfusion of blood of an infected person. Regarding 1,2 and 3 :

asked Jan 6, 2014 by pady_1

1 answer

MTP: 1. MTPs are considered relatively safe during the first trimester. 2. Second trimester abortions are much more riskier. 3. Majority of the MTPs are performed illegally by unqualified quacks which are usually safe. Regarding 1,2 and 3:

asked Jan 6, 2014 by pady_1

1 answer

In tubectomy: 1. A small part of the fallopian tube is removed or tied up 2. It is done through a small incision in the abdomen or through ******. 3. This technique are least effective 4. But their reversibility is good. Regarding 1,2 and 3:

asked Jan 6, 2014 by pady_1

1 answer

In vasectomy: 1. A small part of the vas deferens is removed or tied up 2. It is done through a small incision on the ******* 3. Its reversibility is very poor. Regarding 1,2 and 3:

asked Jan 6, 2014 by pady_1

1 answer

1. Progestogens alone or in combination with estrogen can also be used by females as injections or implants under the skin. 2. Their mode of action is similar to that of pills 3. Their effective periods are short. Regarding 1,2 and 3:

asked Jan 6, 2014 by pady_1

1 answer

Regarding Oral Contraceptive pills: 1. Pills have to be taken daily for a period of 21 days starting preferably within the first five days of menstrual cycle. 2. After a gap of 7 days, it has to be repeated in the same pattern till contraconception is desired. 3. Menstruation occurs in between the 21 day course of tablet. Regarding 1,2 and 3:

asked Jan 6, 2014 by pady_1

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