NEET Test 55

Any electric dipole in a uniform electric field experiences a torque but since here, the electric field is not uniform, the forces which make the couple do not cancel and hence there will be an additional translational force acting on the dipole along with the torque.

Polymeric hydrides are hydrides of beryllium and magnesium. Large number of BeH₂ units are combined to form covalent hydrides.

Calcination is a process of heating a substance to a high temperature but below the melting or fusion point, causing loss of moisture, reduction or oxidation and dissociation into simpler substances.

[Co(NH₃)₃Cl₃] has geometrical isomers as facial and meridional arrangement. Both the arrangement contains plane of symmetry and hence does not show optical isomerism. For the other complexes there exists optical isomers. 
Hence, the correct option is C.

• Biomass refers to the amount of living matter (expressed as weight) at any trophic level at a given time.
• Forest ecosystem system involves organisms of all the trophic level, therefore it occupies the maximum biomass as compared to Lake, Pond and Grassland ecosystem.
• Forests are the one of the most productive areas on earth.
• More than half of different varieties of animals and plants in the world live in theforests.
• The abundant sunlight, warm temperatures, and daily rain lead to a fast turnover of nutrients, and plant growth is rapid, therefore, forest ecosystem have high productivity that contributes to maximum biomass.

• Carbon is the component of all organic compounds of protoplasm like carbohydrates, lipids, nucleic acids, enzymes, hormones etc.
• It constitutes 49% of dry weight of organisms.
• Carbon cycling occurs through atmosphere, ocean and through living and dead organisms.
• 4*10³ kg of carbon is fixed in the biosphere through photosynthesis annually.
• Some fixed amount of carbon is lost to sediments, shells, skeletons and removed from circulation.

• There are four major causes of loss of Biodiversity i.e., Habitat loss and fragmentation, Over-exploitation, Co-extinctions and Alien species invasion.
• Out of these four Habitat losses and fragmentation is the most important cause of the biodiversity loses which is driving plants and animals to extinction. Examples of habitat loss and fragmentation are-

(a) The Amazon rain forest harboring probably millions of species is being cut and cleared for cultivating soya beans or for conversion to grasslands for raising beef cattle. 
(b) Eutrophication of water bodies drastically reduces species diversity.