CAPF (AC) 2020 (Paper-1) (Question 1-50)

The permanent hardness of water is due to the presence of chlorides, nitrates and sulphates of calcium and magnesium in the water. There are various methods of removal of this hardness as simple methods like boiling. lime treatment, Permanent hardness can be removed by Ion Exchange Resin Method, Gan's Permutit Method.

Calgon's Process, etc. But bubbling SO, cannot help in the removal of permanent hardness. Thus, options a, b, and c are correct and option D is incorrect.

Polyaromatic hydrocarbons are not one of the components of Photochemical smog. When oxides of nitrogen are exposed to ultraviolet radiation they undergo a complex series of hydrocarbon reactions to produce the photochemical smog components.

These components include a mixture of ozone, aldehydes, nitric acid, peroxyacyl nitrates and many other secondary pollutants.

• Photochemical smog is also known as "Los Angeles smog".
• Photochemical smog occurs most prominently in urban areas that have large numbers of automobiles (Nitrogen oxides are the primary emissions).
• Photochemical (summer smog) forms when pollutants such as nitrogen oxides (primary pollutant) and organic compounds (primary pollutants) react together in the presence of SUNLIGHT. A gas called OZONE (Secondary pollutant) is formed.

Nitrogen Dioxide + Sunlight + Hydrocarbons = Ozone (Ozone in stratosphere it is beneficial, but near the earth’s surface it results in global warming as it is a greenhouse gas)

• The resulting smog causes a light brownish coloration of the atmosphere, reduced visibility, plant damage, irritation of the eyes, and respiratory distress.

The eukaryotic chromatin is composed of DNA and protein. Chromatin is a highly organized complex of DNA and proteins and is a principal component of the cell nucleus. It helps in the organization or packaging of DNA inside the nucleus.

The structure of chromatin is governed by a number of factors. The complete structure mainly depends on the phases of the cell cycle. They undergo various structural changes during cell division. The structure of
chromosomes is clearly visible under a light microscope during metaphase, which changes their shape while the DNA is duplicated and divided into two cells.
There are 3 stages in the chromatin group:
1. Nucleosomes are formed by the wrapping of DNA around the histone proteins
2. Multiple histones wrap into a 30 nm fibre consisting of the nucleosome.
3. Higher-level DNA packaging of the 30 nm fibre into the metaphase chromosome.

The animal with bilateral symmetry and triploblastic body without true coelom is placed in the phylum Platyhelminthes. These are commonly known as flatworms. Flatworms have no body cavity other than the gut and lack an anus and use pharyngeal opening for both intake of food as well as waste excretion.

The actual site of gaseous exchange in the human respiratory system is alveoli. Here exchanges of gases take place between alveoli and blood capillaries by oxygen entering the bloodstream and carbon dioxide exiting. It is through this mechanism that blood is oxygenated and carbon dioxide, the waste product of cellular respiration, is removed from the body.

Adrenaline is a stress hormone that is produced within the adrenal gland and secreted into the blood. It alters the heartbeat, strengthens the force of the heart's contraction and opens up the bronchioles in the lungs.

• Adrenaline serves a purpose by helping you react in a dangerous situation. But there are times when it’s not helpful to your body. Nicotine makes your body release adrenaline, which causes your heart to beat faster and your blood pressure to rise. High blood pressure is bad because it makes
  your heart work harder.
• When anxiety causes panic attacks, your body releases adrenaline because it thinks you’re in danger. These attacks put your body under stress each time, making your heart work harder.

The chemical which crosses the synapse between nerve cells is released from the nerve endings of nerve cells. The arrival of a nerve impulse at the presynaptic terminals causes the movement toward the presynaptic membrane of membrane-bound sacs, or synaptic vesicles, which fuse with the membrane and release a chemical substance called a neurotransmitter.

The major function of Platelets or thrombocytes is blood clotting. If a blood vessel wall becomes damaged, platelets help in cot formation at the site of damage. Platelets stop blood loss by clotting and clogging arteries.

• Platelets, or thrombocytes, are small, colorless cell fragmentsin our blood that help with clotting.
• Platelets are your body’s natural bandage to stop bleeding.
• Platelets form in the soft tissue of your bones (bone marrow). The largest cells in your bone marrow (megakaryocytes) make platelets.
• They form in the shape of a plate, which is where they get their name.
• They are smaller than red or white blood cells.

As per de Broglie equation λ=h/p or in the question it is given that both electrons and the photons have the same
De Broglie wavelength,
therefore for electrons, De Broglie wavelength
λε = h/p

For Photon, λp = h/p this means if h (Planck's constant), the wavelength is the same then the linear momentum (p) must be the same hence, if electrons and the photons have the same De Broglie wavelength they both have the same linear momentum.

Oil has a surface tension of 35 dynes/cm while water gas is 72 dynes/cm. Due to this large variation between this Water and oil do not mix.

• Qil and water are said to be immiscible, meaning they do not mix to form a homogeneous solution. This is because the forces between water molecules (hydrogen bonds, which are strong cohesive forces) are much stronger than the forces between oil molecules (van der Waals forces, which are weaker).
  More importantly, the adhesive forces (forces between different types of molecules) between oil and water molecules are weaker than the cohesive forces within water itself or even within oil.
• When oil and water are mixed, the water molecules would much rather stick together with other water molecules, and oil molecules would rather stick together with other oil molecules, than mix with the other substance.
  The high surface tension of water, driven by its strong hydrogen bonds, plays a crucial role. Water molecules minimize their contact with oil molecules by grouping together, and the oil molecules also cluster together to minimize contact with water. This leads to the formation of separate layers, with the less dense oil typically floating on top of the water.
• The interface between oil and water has a high interfacial tension (a concept related to surface tension, specifically between two immiscible liquids) because of the unfavorable interactions between oil and water molecules compared to their self-interactions. Minimizing this high-energy interface area is achieved by the liquids separating.