Question
What makes the candle flame yellow and luminous?
✓
Answer
When a candle is lighted, the wax melts, rises up the wick and gets converted into vapours. In a candle, there is no provision for the proper mixing of oxygen (of air) for burning wax vapours. So, the wax vapours bum in an insufficient supply of oxygen (of air) which leads to incomplete combustion of wax. This incomplete combustion of wax produces small unburnt carbon particles. These solid carbon particles rise in the flame, get heated and glow to give out yellowish light. This makes the candle flame yellow and luminous.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
An object is placed 20cm from (a) a converging lens, and (b) a diverging lens, of focal length 15cm. Calculate the image position and magnification in each case.
Write the characters of each of the following animals with the help of classification chart: Penguin.
Observe the figure 1.5 of translation and translocation, given on page 9 this chapter and answer the following questions:
(1) Which is the initiation codon? Where is it present?
(2) What are the types of RNA present inside the ribosome? Which triplet codon is present on it?
(3) Which genetic code is present on mRNA that is leaving the nucleus? What must be the sequence on the DNA to have such code on mRNA?
(1) Which is the initiation codon? Where is it present?
(2) What are the types of RNA present inside the ribosome? Which triplet codon is present on it?
(3) Which genetic code is present on mRNA that is leaving the nucleus? What must be the sequence on the DNA to have such code on mRNA?
| Column A | Column B |
| (1) Magnification | (a) $\frac{1}{f}$ |
| (2) Power of a lens | (b) $\frac{h_2}{h_1}$ |
| (3) Focal length | (c) $f$ |
| (4) Distance of an object from a lens | (d) $u$ |
| (e) $\frac{h_1}{h_2}$ |
Some of the important fossils which have been studied are those of organisms X, Y and Z. X were marine arthropods which were common between 400 to 600 million years ago. Y were the invertebrate animals (molluscs) with a flat, coiled, spiral shell which lived in the sea about 180 million years ago. Z are the extinct carnivorous or herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z?
Give reasons for the following observations:
- Air holes of a gas burner have to be adjusted when the vessels being heated get blackened by the flame.
- Use of synthetic detergents causes pollution of water.
Explain with suitable examples importance of anatomical evidences in evolution.
###
Explain the importance of Anatomical evidences with examples.
###
Explain the importance of Anatomical evidences with examples.
An object is 24cm away from a concave mirror and its image is 16cm from the mirror. Find the focal length and radius of curvature of the mirror, and the magnification of the image.
What is a thermite reaction? Explain with the help of an equation. State one use of this reaction.
(Nocardia, Geobacter, Ideonella sakaiensis, Pseudomonas, Alcanovorax borkumensis, hydrocarbonoclastic, Acidophillium, streptomyces)
Bacteria like ………… spp. and ………. have the ability to destroy the pyridines and other chemicals. Hence, these bacteria are used to clear the oil spills. These are called ………. bacteria. It has been observed that species like Vibrio, …………… can decompose the PET. Similarly, species of fungi like ………… have ability of decomposing rubber from garbage. Sulphuric acid is source of energy for some species of bacteria like ………… Hence, these bacteria can control the soil pollution occurring due to acid rain. …………..convert the salts of uranium into insoluble salts.
Bacteria like ………… spp. and ………. have the ability to destroy the pyridines and other chemicals. Hence, these bacteria are used to clear the oil spills. These are called ………. bacteria. It has been observed that species like Vibrio, …………… can decompose the PET. Similarly, species of fungi like ………… have ability of decomposing rubber from garbage. Sulphuric acid is source of energy for some species of bacteria like ………… Hence, these bacteria can control the soil pollution occurring due to acid rain. …………..convert the salts of uranium into insoluble salts.