Question Paper

AHSEC (Assam higher secondary education council), HS final exam question paper 2018

HS final exam question paper 2018

AHSEC (Assam higher secondary education council), HS final exam question paper 2018

AHSEC,HS final exam question paper 2018/ class 12 Assam HS final exam question paper of the year 2018 and previous year question paper/ H.S. Science 2nd year question paper 2018 are available on this site. The question papers are available in the pdf format. The questions papers of the subjects are physics, chemistry, mathematics, biology, assmaese and English. And also some important topics of the paper of physics, chemistry, mathematics, biology and English

Assam higher secondary education council has conducted the Assam higher secondary board exams (science, arts, and commerce) every year from February to march month, and the results will be declared in the month of May/June every year.

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Mathematics

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Physics

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Chemistry

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Biology

 

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English

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Assamese

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Some important topics of chemistry

Types of semiconductor

  There are two main types:-
i )Intrinsic Semiconductor: Eg- Si,Ge,Sn etc.
ii)Extrinsic Semiconductor: Eg- n-type or p-type.
Dopping:
The conductive power of intrinsic semiconductor can be increase by introducing electron deficient or electron rich impurities in to the crystal of intrinsic semiconductor . Such a process is known as dopping.
n-types semiconductor:
  When the elements of 14 group like C,Si,Ge,Sn,Pb are dopped with the elements of 15 group like N,P,As,St,Bi an n-type semiconductor is produces.
   Po As has 5 valances electron out of which for electrons are used in shearing with Si. The 5th valance electron remains free to move. As a result conducting capacity increases. Since the conducting power increases due to a negative charge (electron) such semiconductors are called negative type or n-type semiconductor.
   P-type:
     When the elements of 14 group are doped with the elements of 13 group like B,Al,etc a p-types semiconductor is produced. Al has 3 valance electron and the 4th valency of Si remain vacant known as electron hole or positive hole.
 Electron from the neighboring site move towards the electron hole and produced another hole in its original site. In the presence of electric field ,the electrons move towards the positively charged plate through the electron hole.

Magnetic properties:

   Based on the effect of magnetic field they are divided into 5 types-
   1) Para-magnetic:
       Substances having one or more unpair electron are weakly attracted by magnetic field. Such substances are called para-magnetic and phenomenon is called para-magnetism.
  eg: Fe3+,Cu2+,O2 etc.
2) Dimegnetic:
      Substances having no unpair electron are called dimagnetic.
  eg: H2O,NaCl,N2,etc.
3)Ferrimegnetic:
      Substances like Iron,Cobalt,Nickel,CrO2 etc are strangely attracted by magnetic field . Such substances are called Ferrimegnetic and the phenomenon is called ferrimegnetism. In ferrimagnetic substance the domains are oriented in the same direction with the direction of external magnetic field . Therefore the next magnetic moment is very high.
4)Anti-ferrimagnetic:
      Substances like MnO are called Anti-ferrimagnetic substances. They are not attracted by magnetic field. In this substance the domain are oppositely oriented and the net magnetic moment become 0.
5)Ferromegnetic:
     When the domains are oriented in parallel and antiparallel direction in unequal number there is net magnetic moment which is less then that of ferrimegnetic substance . Such substance are weakly attracted by magnetic field. This are known as ferromegnetic substance and the phenomenon is known as ferromegnetism . eg : Fe3O4, ZnFe2O4, MgFe2O4

Some important questions answer of the subject Biology

Q. Write down difference between placental mammal and marsupial mammals?

Answer:

★ Placental mammal has a placenta which is an organ develops in the uterus during pregnancy. It provide nutrients and oxygen to the growing baby and removes waste products from baby’s blood till birth so gestation period is long.

★ Marsupials have short gestation time due to having a yolk type placenta. Due to this they day give birth very early and the young animal or helpless embrace climbs from the mother’s birth canal and reach nipples in the pouch. Their are called mammals because mammary gland (nipples) and true hairs are present.

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