Answer:
I think no C or D
if wrong correct me plsssssss
Mark me brainliest plsss
Explanation:
December 21 marks the winter solstice in the Northern Hemisphere, but in 2020 the longest night of the year is also going to be a witness to an incredible astronomic event known as the “great conjunction”. ... This rare double planet sighting–or “Great Conjunction”–can be viewed from anywhere around the globe
You might have meant hemiacetal, not hemicetal.
Acetals contain two –OR groups, one –R group and a –H atom. In hemiacetals, one of the –OR groups in acetals is replaced by a –OH group<span>.
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Explanation:
A chemical bond which is formed in between positively charged atoms when there is sharing of free electrons in a lattice of cations is known as a metallic bond.
In a pure metal, atoms are surrounded by free moving valence electrons which move from one part of metal to another.
Thus, we can conclude that pure metals are held together by metallic bonds due to attraction between mobile valence electrons and positively charged metal ions.
69. The student's skin was obviously warmer than the initial temperature of the bracelet. According to the second law of thermodynamics, heat transfers from a higher temperature to a lower temperature hence heat transfers from the student's skin to the bracelet warming up the bracelet.
70. moles of copper=mass of copper/molar mass of copper
=30.1g/(63.55g/mol)= 0.4736 moles Cu
71. Delta H( heat released) = mCp(deltaT) = 30.1g(0.385 J/gK)(33-19)K = 162.23J
72. Copper is chemically less active than iron.