• The noble metals are a group of metals that resist oxidation and corrosion in moist air. The noble metals are not easily attacked by acids. They are the opposite of the base metals, which more readily oxidize and corrode.
• There is more than one list of noble metals. The following metals are considered noble metals (listed in order of increasing atomic number):
Sometimes mercury is listed as a noble metal. Other lists include rhenium as a noble metal. Strangely, not all corrosion-resistant metals are considered to be noble metals. For example, although titanium, niobium and tantalum are extremely corrosion-resistant, they are not noble metals.
Question:Consider the following statements.
1. Vascular tissue of the complex plants has made possible their survival in the terrestrial environment.
2. Phloem consists of tracheids, vessels, companion cells and phloem fibers.
Which of the above statements is/are FALSE?
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 Nor 2
Phloem is made up of four types of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma. Xylem consists of tracheids, vessels, xylem parenchyma.
Question:Calcium level decreases in the blood due to hyposecretion of -View
(a) Parathyroid Hormone
(d) ACTH hormone
Parathormone is secreted from parathyroid gland. This hormone helps to regulate the metabolism of calcium and certain other minerals like phosphate. Combined effect of parathormone and calcitonin normally maintain the blood calcium level.
Most commercially available antacids are combinations of aluminum and magnesium hydroxide. Some effervescent antacids contain sodium bicarbonate, that old household remedy for tummy aches known as “baking soda.”
Question:Why do we get muscle cramps after heavy exercise?.
(a) Shortening of myofibrils
(b) Reduction in myosin
(c) Lengthening of myofibrils
(d) Muscle Cells respire anaerobically
The cramps occur when muscle cells respire anaerobically. The partial breakdown of glucose produces lactic acid. The accumulation of lactic acid causes muscle cramps. We get relief from cramps after a hot water bath or a massage. Hot water bath or massage improves circulation of blood. As a result, the supply of oxygen to the muscle cells increases. The increase in the supply of oxygen results in the complete breakdown of lactic acid into carbon dioxide and water.
Question:Crooke’s glass that cuts harmful ultra violet rays that are harmful to eyes contains -View
• Tasar is copperish colour, coarse silk mainly used for furnishings and interiors. It is less lustrous than mulberry silk, but has its own feel and appeal. Tasar silk is generated by the silkworm, Antheraea mylitta which mainly thrive on the food plants Asan and Arjun.