Answer:
Please check with the attachment posted.
Please do confirm the answer.
44. (a) N2O3 (b) SF4 (c) AlCl3 (d) Li2CO3
46. H Br
δ+ δ−
48. The metallic potassium atoms lose one electron and form +1 cations,
and the nonmetallic fluorine atoms gain one electron and form –1 anions.
K → K+
+ e–
19p/19e–
19p/18e–
F + e–
→ F–
9p/9e–
9p/10e–
The ionic bonds are the attractions between K+
cations and F–
anions.
50. See Figure 3.6.
52. (a) covalent…nonmetal-nonmetal (b) ionic…metal-nonmetal
54. (a) all nonmetallic atoms - molecular (b) metal-nonmetal - ionic
56. (a) 7 (b) 4
58. Each of the following answers is based on the assumption that nonmetallic
atoms tend to form covalent bonds in order to get an octet (8) of
electrons around each atom, like the very stable noble gases (other than
helium). Covalent bonds (represented by lines in Lewis structures) and lone
pairs each contribute two electrons to the octet.
(a) oxygen, O
If oxygen atoms form two covalent bonds, they will have an octet of electrons
around them. Water is an example:
H O H
(b) fluorine, F
If fluorine atoms form one covalent bond, they will have an octet of electrons
around them. Hydrogen fluoride, HF, is an example:
H F
(c) carbon, C
If carbon atoms form four covalent bonds, they will have an octet of electrons
around them. Methane, CH4, is an example:
H H
H
H
C
(d) phosphorus, P
If phosphorus atoms form three covalent bonds, they will have an octet
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).
144 years, its simple math?
