The presence of oxidizing acids; heavy-metal salts, sulfur, and ammonia; and a number of sulfur and ammonia compounds can cause corrosion to set in. Water that comes from a well is much more likely to contain these materials and put copper lines in jeopardy—but it can occur in the civic water system as well.
Copper corrodes at insignificant rates when used in areas with unpolluted air, non-oxidizing acids, and water. However, it happens more rapidly with the presence of road salt, ammonia, sulfur, oxidizing acids
Acidic substances react with the surface of copper, causing it to tarnish and corrode almost instantly. This corrosion is highly soluble, leading to the presence of toxic copper salts in the food. This is why it is not recommended to use copper vessels for foods high in acidity, such as milk, wine, or vinegar.
Answer: The stage of metamorphosis this occurs is called the PUPA stage. The correct option is D.
Explanation:
Metamorphosis can be defined as the change in form, mode of life and behaviour that occurs during embryonic development of an organism. In the metamorphosis of insects, which mostly reproduce sexually, insects can be grouped according to the way the eggs develop into adults. Some show:
--> Complete metamorphosis or
--> Incomplete metamorphosis.
In the life cycle of a butterfly, a COMPLETE metamorphosis occurs. This is because after fertilization, the EGG hatches into LARVA which passes through a PUPAL stage before becoming transformed into an ADULT insect. That is:
Egg --> Larva --> Pupa --> Imago.
When the caterpillar, which is the Larva stage, has reached its full size, it spins a pad of silk on a twig. It moves upward and attached it's clasper to this pad. It spin another silk thread at the thorax. These aids it to assume a slanting position with the head end pointing upwards. The pupa stage called the CHRYSALIS is reached when it tucks it's head under its thorax, arches it's body, shortens and broadens, and moults for the last time. Therefore the correct option is D (pupa).
