List of top Science Questions

The movement of the sunflower plant is a response to which type of stimulus?

Name the part performing the following functions in the human female reproductive system: 
(i) Production of eggs 
(ii) Site of fertilization 
(iii) Site of implantation 
(iv) Entry of the sperms 

What is a rainbow? 'We see a rainbow in the sky only after the rainfall.' Why?
Out of the two media - Medium 1 and Medium 2, in which is the speed of light more?
path of a ray of light going from Medium 1 to Medium 2
Identify from the following the ray diagram which shows the correct path of the reflected ray for the ray incident on a concave mirror as shown:
path of the reflected ray for the ray incident on a concave mirror
Assertion (A): Concentrated nitric acid is diluted by adding water slowly to acid with constant stirring.
Reason (R): Concentrated nitric acid is easily soluble in water.
In the light of the above statements, choose the most appropriate answer from the options given below:
In which of the following reactions is a combination reaction taking place?
I. CuO + H$_2$ $\xrightarrow{\Delta}$ Cu + H$_2$O
II. ZnO + C → Zn + CO
III. 4Na + O$_2$ → 2Na$_2$O
IV. CH$_4$ + 2O$_2$ → CO$_2$ + 2H$_2$O
In our houses we receive A.C. electric power of 220 V. In electric iron or electric heater cables having three wires with insulation of three different colours – red, black and green are used to draw current from the mains. What are these three different wires called? Name them colourwise. What is the potential difference between the red wire and the black wire? What is the role of the wire with green insulation in case of accidental leakage of electric current to the metallic body of an electrical appliance?
The minimum number of identical bulbs of rating 4V, 6W, that can work safely with desired brightness, when connected in series with a 240V mains supply is:
A tall pea plant with round seeds (TTRR) is crossed with a short pea plant with wrinkled seeds (ttrr). The F1 generation will be:
Name a metal found in the earth's crust:
(i) in free state and
(ii) in the form of its compound.
State where each of these metals are placed in the reactivity series of metals
Give one example each of a unisexual flower and a bisexual flower. Mention the changes which a flower undergoes after fertilization.
Give two methods used to grow rose and jasmine plants by vegetative propagation.
Mention any two ways by which plants absorb carbon dioxide. Also explain the reason for opening and closing of stomata.
While burning a magnesium ribbon in air, list two safety measures which should be followed. Also state two observations of this activity.
"Sex of a newborn baby in humans depends on the father, not the mother." Confirm this statement with the help of a flow chart.
"Proteins control the expression of various characters." Explain this statement by taking an example of "tallness" as a characteristic in plants.
What is photosynthesis? Name the organs and organelles (cell structures) where photosynthesis occurs.
Where is oxygen released during this process? What happens to the carbohydrates that are not immediately used by plants?
Write the chemical formula of bleaching powder. Write the balanced chemical equation for its preparation. List three uses.
Draw a ray diagram to show image formation by a concave mirror when the object is placed between focus and center of curvature.

As shown in the diagram, an electron enters perpendicularly into a magnetic field. Using Fleming’s Left-Hand Rule, determine the direction of the force experienced by the electron. 

Write a four-step aquatic food chain. Among them, which group of organisms is most important and why?
A person must hold reading material at a distance greater than 25 cm for clear vision.
(i) What is the name of this visual defect?
(ii) Draw a ray diagram to show its correction.
With the help of a labeled diagram, show the pattern of magnetic field lines around a current-carrying straight conductor. Explain how we can use the right-hand thumb rule to find the direction of magnetic field due to current.
Assertion (A): Both plants and animals exhibit chemical coordination.
Reason (R): Plant hormones regulate directional growth while in animals, hormones do not control directional growth.