Which one is a weak acid?

• Citric acid

• Nitric acid

• Sulphuric acid

• Hydrochloric acid

Which scientist was developed the 'key' for the identification of animals?

• Goethe

• Cuvier

• John Ray

• Theophrastus

Seedless fruits are of no use in

• Coconut

• Tomato

• Banana

• Grape

HIV mainly infects

• Cytotoxic T-lymphocytes

• Helper lymphocytes

• Killer lymphocytes

• Cell mediated T-lymphocytes

Down's syndrome is caused due to

• monosomy of 21st chromosome

• trisomy of 21st chromosome

• an extra chromosome in male

• an extra chromosome in female

Which one of the following plants keeps its stomata open during the night and close during the day?

• Water-lily

• Cactus

• Cycas

• Orchid

Which equation shows the reaction of photosynthesis?

• CO₂ + H₂O → CH₂O + O₂

• 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

• 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

• C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

The change in temperature of a body is 50°C. The change in temperature on the Kelvin scale is

• 50 K

• 323 K

• 122 K

• 70 K

Total internal reflection is possible when light travels from

• air to water

• air to glass

• water to glass

• glass to water

A body of mass 2 kg is moving on a smooth horizontal surface with an initial velocity of 10 ms^-1 along the east. A uniform force of 10 N towards the north is applied to the body. The final velocity of the body after 2 s will be

• $10\sqrt{2}$ ms^-1 at 45° North of East

• $10\sqrt{2}$ ms^-1 at 45° South of East

• 20 ms^-1 towards East

• 20 ms^-1 towards West