Chemistry 2024 – Question 63
Chemistry 2024 – Question 63
Consider the following table
| Substance | Melting point / °C | Boiling point / °C |
|---|---|---|
| P | -78 | -25 |
| Q | -8 | 40 |
| R | -6 | 150 |
| S | 44 | 280 |
Which of the substances is a liquid at room temperature and rapidly evaporates on exposure to air?
Explanation
Sexual reproduction involves flowers. Male part (stamen): anther produces pollen, filament supports it. Female part (pistil): stigma receives pollen, style connects to ovary containing ovules.
Pollination transfers pollen to stigma (by wind, insects, birds). Fertilization occurs when pollen tube grows down style; sperm meets egg in ovule. Fertilized ovule becomes seed; ovary becomes fruit.
Asexual/vegetative reproduction: runners (strawberry), tubers (potato), bulbs (onion), stem cuttings. Produces genetically identical offspring (clones). Faster but no genetic variation.