RRB JE Electrical solved question paper 2015 | RRB JE Electrical

Answer.3. HCl

Explanation:-

Covalent bonds are formed by sharing electrons between non-metals to reach a stable valence configuration. The formation of a bond between H and Cl to give an HCI molecule can be represented as

As the two atoms approach each other, unpaired electrons on each atom pair up to form a covalent bond. The pair of electrons is shared by the two atoms. Each atom then acquires a noble-gas configuration of electrons, the H atom having two electrons about it (as in He), and the Cl atom having eight valence electrons about it (,as in Ar).

Answer.4. Double Displacement

Explanation:-

Those reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions. 

The reactions between acids and bases to form salts and water are double displacement reactions. For example, sodium hydroxide and hydrochloric acid react to form sodium chloride and water:

NaOH + HCl → NaCl + H₂O

In this double displacement reaction, two compounds, sodium hydroxide, and hydrochloric acid react by an exchange of ions to form two new compounds, sodium chloride, and water.

Answer.1. Carbon dioxide

Explanation:-

The acid reacts with a metal carbonate or metal hydrogen carbonate to form salt, water, and carbon dioxide gas released with brisk effervescence

Acid + Metal carbonate/Metal bicarbonate → Salt + Water + Carbon dioxide

For example,

NaHCO₃ (s) + HCl (aq) → NaCl (aq) + CO2 (g) + H₂O (L)

Answer.3. It has the elements arranged in order of their increasing atomic numbers

Explanation:-

Mendeleev’s Periodic Table

According to Mendeleev, the properties of elements were related to their atomic weights. On this basis, he formulated his periodic law. Mendeleev’s periodic law states that the physical and chemical properties of the elements are the periodic functions of their atomic weights. Therefore, the elements have been arranged in the increasing order of their atomic weights. He compiled a periodic table by arranging the 63 elements known then in eight vertical columns called groups and seven horizontal rows known as periods. Later, when the noble gases were discovered, Mendeleev gave a modified periodic table by including the noble gases in zero groups. He categorized the table into eight (columns) groups and seven periods (rows). The groups range from zero to eight and these except the zero and the eighth group was further subdivided into two subgroups A and B. He numbered the periods from 1 to 7 of which the seventh period is incomplete.

Merits of Mendeleev’s Periodic Cable

1. Mendeleev left some gaps for some undiscovered elements in the periodic table. The properties of these elements could be predicted based on the properties of other elements present in the same group. He named these missing elements as Eka boron, Eka aluminum and Eka silicon that were later discovered and named as scandium, gallium, and germanium, respectively.
2. Mendeleev corrected the doubtful atomic weights of some elements like indium, beryllium, and uranium.
3. One of the strengths of Mendeleev’s periodic table was that when inert gases were discovered they could be placed in a new group without disturbing the existing order.

Answer.4. Excreting excess hormones present in the blood

Explanation:-

Function of the Kidneys

The kidneys perform the primary functions of the urinary system.

Excretion of Waste and Foreign Substances:-The production of urine in the kidneys allows waste products such as ammonia, urea, bilirubin and creatinine to be excreted from the body. Foreign substances such as environmental toxins and drugs can also be eliminated in urine

Vitamin D Hydroxylation and Calcium Maintenance:-The kidneys maintaining calcium levels via the hydroxylation of inactive vitamin D and the production of the active form of vitamin D, 1,25-dihydroxy vitamin (calcitriol), in the proximal tubule.

Erythropoietin and Red Blood Cells:-The kidneys are involved in red blood cell production via; the production of erythropoietin.

Maintenance of Blood Osmolarity: – A constant blood osmolarity of approximately 290 mOsm/L is maintained due to the regulation of solutes conserved or excreted in urine.

Regulation of the ionic Composition of Blood:- The calcium, chloride, phosphate, potassium and sodium ion levels in the blood are all regulated by the kidneys.

Regulation of Blood pH:- The pH of the blood (7.35-7.45) is regulated through the excretion (of hydrogen ions) and conservation (of bicarbonate ions) of ions into the urine.

Regulation of Blood Volume and Pressure:- The elimination of fluids from the body in the form of urine and the conservation of fluids in the body aid in the regulation of both blood volume and blood pressure. m. An increase in renin release leads to an increase in blood pressure, due to an increase in sodium and water reabsorption in the renal tubules.

Regulation of Blood Glucose Levels:- Glutamine is used by the kidneys in the process of gluconeogenesis, in which glucose is synthesized. The glucose thus formed can then be released into the bloodstream to aid in the maintenance of a steady blood glucose level. Glucose counter-regulation can then be achieved. 

Reabsorption and Filtration:-Urine is formed in two stages. First, blood is filtered into the kidney tubules to form a clear fluid (i.e. a filtrate) which contains the Waste substance urea and many useful substances which the body cannot afford to lose. Second, the useful substances are reabsorbed from the filtrate back into the blood leaving only urea and other substances in the kidney tubules which are of no use to the body. The technical words for these two stages are filtration and reabsorption. 

Answer.3. Fish, Amphibians, Reptile, Birds, Mammals

Explanation:-

Answer.3. Green leaves in any plant and stem in cacti

Explanation:-

The process by which green plants make their own food (like glucose) from carbon dioxide and water by using sunlight energy (in the presence of chlorophyll) is called photosynthesis. 

Photosynthesis by Plant Parts Other Than Leaves

Normally photosynthesis takes place only in the leaves of plants In some plants, however, photosynthesis also takes place in other parts of plants such as “green stems” and “green branches”. The green stems and green branches can do photosynthesis because they contain chlorophyll. For example, desert plants such as cactus have tiny, spine-like leaves to reduce the loss of water by transpiration. These tiny, spine-like leaves of a cactus plant cannot do photosynthesis. The stem and branches of a cactus plant are green which contain chlorophyll. So, the green stem and green branches of a cactus plant carry out the process o photosynthesis to make food for the plant. Please note that only those stems and branches which are green in colour can do photosynthesis Now, the stems and branches of all the plants and trees are not green So, the stems and branches of all the plants and trees cannot do photosynthesis.

Answer.3. Pollen grain is to an ovule

Explanation:-

Fertilization (fusion of sperm and egg) is the same as Pollen grain to the ovule. Pollen grain contains two sperm nuclei.

Answer.3. Genetic diseases

Explanation:-

Thalassemia is a genetic blood disorder. Abnormal hemoglobins cannot carry sufficient oxygen, and their precipitation damages the red cell membrane, leading to hemolysis (destruction of red cells).

Answer.2. Carbon dioxide

Explanation:-

During combustion and decomposition of plants & animal Co₂ is released. During the respiration process oxygen is inhale while carbon dioxide is exhaled.