Ba2+ and Cu2+, and Sr2+ and Li+
Answer:
A bonding that occurs between high electronegative atoms such are N, F, O and H atoms, is called a hydrogen bond. Hydrogen bond is a very strong bond. (C)
If hydrogen bonds are not formed between H atoms and N, F, O atom, then the atoms interact through dispersion forces (also known as london dispersion forces). Dispersion forces are weak and they are temporary forces formed by overlapping of orbitals. (B)
Main advantages of DDT are the insecticide property and the knoledge about its chemical synthesis.
Explanation:
At that time in 1939 it was discovered that DDT have insecticide properties. It is a useful property because it allows inhibition of insects populations in large areas. Killing insects will reduce the diseases transmitted by them as typhus and malaria. More over you prevent the destruction of the agricultural crops by the harmful insects.
However the synthesis of the molecule was known way back in 1874. From that time it was plenty of time in which chemistry knowledge evolved so the synthesis at kilograms scale was implemented. High quantities of DDT molecule become available for the market so that in 1945 was available as agricultural insecticide.
It was discovered that DDT have bad effects for human health and also over time some insects developed resistance and their were not affected anymore by the molecule.
You may find the chemical structure of DDT in the attached figure.
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Answer:
A chemical change occurred, a gas and precipitate was produced
Explanation:
From the question , we are informed of science lab, where Cash mixes two clear liquids together in a beaker. Bubbles are produced, and a white solid forms and settles to the bottom.
In this case the change that took place is chemical change ( is one where new product are formed after two substance react) the bubbles that is produced signify the presence of gas in the product, white solid formed is reffered to as a precipitate( which is reffered to as solid that is been formed from a particular solution).