Jul 192013

SLC Model Question Set 2 (HPE)

Full Marks: 75
Pass Marks: 24

Group A

Very short answer questions. (1 × 1 = 10)
1. Write one element of population composition.
2. If the annual population growth rate of a place is one percent, over how many years the population will be doubled?
3. Write any one criteria of quality life.
4. Write one measures to mitigate the adverse effects in the ecosystem of Terai region.
5. What is the capacity of animals to adjust in natural environment called?
6. Which species of animals are found more in Nepal?
7. Write down any one measure which can be performed by your own level to conserve biodiversity.
8. Write a measure to control unmanaged urbanization.
9. In which part to the body the human papiloma virus causes cancer?
10. Under whose responsibility does the construction of public latrine fall?

Group B

Short answer questions. (13 × 5 = 65)
11. What is population? Describe in brief about the size of population and growth rate.
12. List the biological factors which affect birth and describe any two of them in brief.
13. The population of a certain district of Nepal was 1,50,000 in 2058. Within that year, 1,000 people died, 2,000 people outmigrated and 1,200 people inmigrated. Now find out CDR and GMR.
14. What efforts can you do to make your life qualitative? Write any five efforts and describe in brief.
15. Explain in brief, the social and economic aspects of the place where you are living.
16. How does garbage management programme helps to conserve the environment? Write shortly.
17. Show the need of conservation of biodiversity.
18. Write short note on any two of the following:
(a) Yarshagumba (b) Python (c) Bengal Tiger
19. Show the relationship of natural resources with development, population and environment.
20. Why should we give priority to the sustainable development while doing development work? Justify your answer with two examples.
21. How is diarrhoea caused? Write down any three symptoms of it.
22. Why do people use tobacco and alcohol? Write any four reasons of using it and any six preventive measures.
23. What is a balanced diet? How can balance diet be prepared from locally available food sources?
24. “Lifestyle of Nepali people is the major health problem of Nepal.” Justify.
25. Write down any five differences between primary health centre and hospital.

CLICK HERE for Previous Set..:::..CLICK HERE for Next Set

Jul 182013

The formation of certain molecules involving Carbon, Boron, Beryllium etc. cannot be explained satisfactorily on the basis of VSEPR (Valence Shell Electron Pair Repulsion) Theory. Hence, a new concept called hybridization is developed to explain the shape of these molecules and also shape and bonding in other molecules adequately.

Hybridization is the process of mixing of dissimilar orbitals of the same atom to give rise to equal number of a new set of orbitals having same energy content and shape.

Types of Hybridization

On the basis of the types and the number of orbitals involved, hybridization can be categories:

1. sp hybridization

The mixing or combination of one ‘s’ and one ‘p’ orbital to form two ‘sp’ hybrid orbitals is known as sp hybridization. The two sp hybrid orbitals are oriented in opposite manner to each other with bond angle 180o. Each hybrid orbital consists of a bigger and a smaller lobe.sp hybridization

For example:

Formation of BeF2
The electronic configuration of central atom Be is 1s22s2. During hybridization, one of the electron is first excited to p orbital with the absorption of energy. And these two half filled orbitals undergo sp hybridization to form two sp hybrid orbitals which combine with two F atoms to form BeF2.
Excited Stage:

sp hybrid orbital

2. sp2 hybridization

The combination of one ‘s’ and two ‘p’ orbitals to form three sp2 hybrid orbitals is called sp2 hybridization. The three hybrid orbitals are oriented towards the corners of a triangle with bond angle 120o. For example:
Formation of BF3

sp2 hybridization

3. sp3 hybridization

The combination of one ‘s’ orbital and three ‘p’ orbitals to form four sp3 orbitals is called sp3 hybridization. The four hybrid orbitals are oriented towards the four corners of a tetrahedron with bond angle 109.5o. For example:
Formation of CH4

sp3 hybridization