Double fertilization : It occurs when one male nucleus fertilizes (fuses) with egg cell to form zygote cell and other male nucleus fuses (fertilizes) with two polar nuclei to cause triple fusion. As these two types of fertilizations take place at the same time in the ovule of the plant, it is known as double fertilization.

The metal B will be nearer to the top of the activity series of metals because this metal is so reactive that it reacts with most elements to form its compounds. But metal A is less reactive as it exists in free state without reacting with other elements.

Eyes of some animal's shine in the night because they have a special type of reflective layer behind the pupil of their eyes known as Tapetum Lucidum which enhances the amount of light absorbed by the photoreceptors in their eyes.

Reproductive health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity, in all matters relating to the reproductive system and to its functions and processes. Sexual and reproductive health care includes preventing and treating sexually transmitted infections, including HIV/AIDS. In addition, reproductive health care can bring patients into the health care system, encouraging diagnosis and treatment of other diseases and conditions.

Answer:

• In birds and mammals have a double circulation system where both the oxygenated and deoxygenated blood maintains separate.
• Warm-blooded animals such as birds and mammals maintain constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment.
• Hence, these animals require more oxygen _(O2) for more cellular respiration so that they can produce more energy to maintain their body temperature.
• It is necessary for them to separate oxygenated and de-oxygenated blood so that their circulatory system is more efficient and can maintain their constant body temperature.
• It is also better if the oxygenated blood stays separate, as its combination with deoxygenated blood will impure the entire blood.

one sperm

Only one sperm fuses with the egg in oviduct to form Zygote. The fertilisation of egg take place in oviduct. 3)The zygote divides rapidly by mitosis as it moves down slowly in oviduct and form a hollow ball of hundred of cells(embryo).

Variations are important for species survival because variation causes the organism to overcome extreme situations. Organism species occupy well-defined positions in the ecosystem, utilizing their reproductive capacity.

Variation beneficial to the species

Even so, for factors beyond the control of the species, such locations will alter, and can even destroy the entire species. If any differences in all of these species were to be found in a few individuals, they would have a chance of surviving.

• Variations can be beneficial or harmful according to the ecological niche of the organism.
• A variation suitable for the particular niche is selected by nature in evolution. Thus variations are necessary for the survival of the species.
• Variation is important for the evolution of the species.

Vegetative propagation is practiced for growing some types of plants because of following advantages:

1. It helps to introduce plants in new areas where seed germination fails to produce mature plants due to changes in environmental factors and the soil.
2. It is a more rapid, easier, and cheaper method.
3. Produces identical quality as the parent.
4. Faster and more certain methods of propagation.

For example, Tuber of potato, the rhizome of ginger.

Natural vegetative propagation are

• Roots. New plants emerge out of swollen, modified roots known as tubers. …
• Leaves. Leaves of a few plants get detached from the parent plant and develop into a new plant.

Relative refractive index : Relative refractive index is the ratio of the speed of light in the medium 1 to the speed of light in medium 2. The value of absolute refractive index may be greater than or less than unity.


Absolute Refractive Index : Absolute refractive index is the ratio of the speed of light in vaccum to the speed of light in the medium. The value of absolute refractive index is greater than unity.

 

The salts which contain water of crystallisation are called hydrated salts.

 For Ex:

1)Copper Sulphate crystals contain 5 molecules of water of crystallisation(CuSO₄.5H₂O)

It is blue in colour.

2)Sodium carbonate crystals contains 10 molecules of water of crystallisation(Na₂CO₃.10H₂O)

3)Calcium sulphate crystals contains 2 molecules of water of crystallisation(CaSO₄.2H₂0)

CH₃COOH

Acetic acid, systematically named ethanoic acid, is a colourless liquid organic compound with the chemical formula CH₃COOH. When undiluted, it is sometimes called glacial acetic acid. Vinegar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. 

The term ‘aqua regia’ is Latin for ‘royal water’.

Aqua regia is a very strong acid formed by the combination of concentrated nitric acid and concentrated hydrochloric acid, both of which are strong acids.

It is generally used to remove metals like gold and platinum from substances, especially in microelectronics and micro-fabrications labs.

It is usually a yellow, reddish-orange, fuming liquid and has a rapidly changing composition.

It is primarily popular for its ability to dissolve gold, palladium and platinum, all of which dont react easily with chemicals.

The reason aqua regia can dissolve gold (and metals like platinum and palladium) is that each of its two component acids

(i.e., hydrochloric acid and nitric acid) carries out a different function. While nitric acid is an excellent oxidizing agent, the chloride ions from the HCl form coordination complexes with gold ions, thereby removing them from the solution.

The reduction of the concentration of Au³⁺ ions shifts the equilibrium towards the oxidized form.

The gold present in aqua regia dissolves completely to form chloroauric acid (HAuCl₄).

The striking surface of the matchbox contains red phosphorus and the head of the matchstick contains potassium chlorate. So when the matchstick is rubbed on the matchbox, some of the red phosphorus is converted to white phosphorus, a chemical i.e. so volatile that it ignites in air.

Metals react with water and produce metal oxides and hydrogen gas. The reaction depends upon the reactivity of metals.

Metals like potassium and sodium react violently with cold water. The reaction of calcium with water is less violent.

Magnesium does not react with cold water. It reacts with hot water to form magnesium hydroxide and hydrogen.

Metals like aluminium, iron and zinc do not react either with cold or hot water.

But they react with steam to form the metal oxide and hydrogen. Metals such as lead, copper, silver and gold do not react with water at all.

Non-metals do not displace hydrogen because they form negative ions by accepting electrons while hydrogen like metals forms a positive ion.

Therefore metals can displace hydrogen while non-metals cannot.

Highly reactive metals like Sodium reacts with dilute hydrochloric acid according to the following equation:

2Na (s) + 2HCl (aq) → 2NaCl (aq) + H₂ (g)

Hydrogen bubbles will be forming in the solution.

Writing in ionic form:-

2Na (s) + 2H⁺¹ (aq) + 2Cl^-1 (aq) → 2Na⁺¹ (aq) + 2Cl^-1 (aq) + H₂ (g)

Both the sodium atoms are neutral.

But hydrogen on the reactants side has +1 charge whereas in product side it is neutral.

Therefore Na donates one electron to each of hydrogen ion.

Less reactive metals like Zinc reacts with dilute acids.

Zn (s) + 2HCl (aq) → ZnCl₂ (aq) + H₂ (g)
It doesnt matter which metal or which acid is used, if there is a reaction we always get hydrogen gas as well as the salt.

However, how quickly the reaction goes depends on the metal used and how high up in the reactivity series it is.

The term ‘aqua regia’ is Latin for ‘royal water’.

Aqua regia is a very strong acid formed by the combination of concentrated nitric acid and concentrated hydrochloric acid, both of which are strong acids.

It is generally used to remove metals like gold and platinum from substances, especially in microelectronics and micro-fabrications labs.

It is usually a yellow, reddish-orange, fuming liquid and has a rapidly changing composition.

It is primarily popular for its ability to dissolve gold, palladium and platinum, all of which dont react easily with chemicals.

The reason aqua regia can dissolve gold (and metals like platinum and palladium) is that each of its two component acids

(i.e., hydrochloric acid and nitric acid) carries out a different function. While nitric acid is an excellent oxidizing agent, the chloride ions from the HCl form coordination complexes with gold ions, thereby removing them from the solution.

The reduction of the concentration of Au³⁺ ions shifts the equilibrium towards the oxidized form.

Bleaching powder is needed in the manufacture of chloroform. Bleaching powder (CaOCl2​) supplies the necessary chlorine and slaked lime (calcium hydroxide).

CaOCl₂​+H_2​O→Ca(OH)_2​+Cl₂​

A paste of bleaching powder in water is distilled with ethanol or acetone to obtain chloroform.

Carbon tetrachloride, also known as tetrachloromethane, is an organic compound with the chemical formula CCl4. This compound is often classified as a polyhalogenated organic compound since it consists of a carbon atom which is attached to more than one halide functional group.

Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), as shown.<a href="https://en.wikipedia.org/wiki/File:Vinyl_chloride_Polymerization_V1.svg" title="The polymerisation of vinyl chloride"></a>

Hydrolysis is a common form of a chemical reaction where water is mostly used to break down the chemical bonds that exists between a particular substance.

The general formula of a hydrolysis reaction is:

AB+H₂O→AH+BOH

Radical

    Radical is an atom or a group of atoms of same or different elements which behaves like a single atom with a positive or a negative charge on it. 

    Radicals have their own combining power based on which they form chemical formulae. 

 Example: 

    NH₄⁺, Na⁺, NO₃⁻, SO₄²⁻ 

The full form of TNT is Trinitrotoluene. TNT is a yellow solid that is often seen as a reagent in the chemical synthesis process but is commonly known for being an explosive substance with smooth handling characteristics.

Chemical indicator, any substance that gives a visible sign, usually by a colour change, of the presence or absence of a threshold concentration of a chemical species, such as an acid or an alkali in a solution. An example is the substance called methyl yellow, which imparts a yellow colour to an alkaline solution. When copper reacts with the elements (oxygen, water and carbon dioxide), it turns from its element color of reddish-brown to green. This chemical reaction is hydrated copper carbonate, and a famous example of it is the Statue of Liberty.

Pbs(s) + 4H₂O₂(aq) → PbSO₄(S) + 4H₂O(I)

Saturated fat is also known as solid fat. Saturated fat in fish and poultry is less when compared to animal fat or red meat. This fat can increase your cholesterol levels. Tropical oils such as cocoa butter, coconut oil, palm oil also have saturated fats. It is mostly found in non-dairy products and snacks in large quantity. Cakes, butter, cookies are some examples of food containing maximum saturated fats.