List of top Science Questions

What is the chemical formula of ethyl alcohol?
The atomic number of sodium is:
The atomic number of magnesium is 12. What is its valency?
What is the chemical formula of quicklime?
Within which pH range does our body work?
Which of the following is the chemical formula of glucose?
The general formula of an alkene is:
Which one of the following is a clean energy source?
Which of the following gases is used in welding?
The process of coating a layer of zinc on iron is called:
Which of the following acids is found in vinegar?
The absolute refractive index of air is actually:
Mirror used by ENT (Ear-Nose-Throat) doctor is:
The functional group \( >CO \) is called:
How many structural isomers of pentane, having molecular formula \( C_5H_{12} \) are possible?
Which of the following metals is the most ductile?
A metal reacts with oxygen to form a compound with high melting point. This compound is soluble in water. Which of the following elements can it be?
Malachite is an ore of which metal?
The chemical formula of Chalk is:
Write one chemical equation each for the chemical reaction in which the following have taken place:
(i) Change in colour
(ii) Change in temperature
(iii) Formation of precipitate
Mention colour change/temperature change (rise/fall)/compound precipitated along with equation.
(A) (i) Name three techniques/devices used by human females to avoid pregnancy. Mention the side effects caused by each.
(ii) What will happen if in a human female (a) fertilisation takes place, (b) an egg is not fertilised?

OR

(B) (i) Draw a diagram showing spore formation in Rhizopus and label the (a) reproductive and (b) non-reproductive parts. Why does Rhizopus not multiply on a dry slice of bread?
(ii) Name and explain the process by which reproduction takes place in Hydra.
To balance the chemical equation, the values of the coefficients x, y, z, and t must be: Zn(NO₃)₂ → ZnO + NO₂ + O₂
Explain the events that take place once a sperm reaches the oviduct till it becomes a foetus. Write the role of placenta in pregnancy.
The filament of an electric lamp draws a current of 0.5 A, which lights for 2 hours. Calculate the charge that flows through the circuit.
(i) The pH of a sample of tomato juice is 4.6. How is this juice likely to be in taste? Give reason to justify your answer.
(ii) How do we differentiate between a strong acid and a weak base in terms of ion-formation in aqueous solutions?
(iii) The acid rain can make the survival of aquatic animals difficult. How?