Answer:Four types of vaccines are currently available: Live virus vaccines use the weakened (attenuated) form of the virus. The measles, mumps, and rubella (MMR) vaccine and the varicella (chickenpox) vaccine are examples
Answer:
D
Explanation:
Without gravity, any object wont go to the ground, and without a magnetic field, a compass cant be used for navigation.
Answer:- none
Explanations:- For naming hydrocarbons we use the suffix -ane, -ene and -yne.
-ane is used when we have only single bonds between all carbons. -ene is used if there is any double bond between two carbons and the -yne is used if there is any triple bond between two carbons.
The given name of the compound is propane. It ends at -ane and so it's an alkane and must have single bonds between all the carbons it has. So, there are zero double bonds present in 
.
This is also clear from the below lewis dot structure of the compound.
It is important to have the correct bond angles of the different atoms and the shape of the molecule due to following reasons;
Among other properties the polarity of compounds mainly depend upon the shape and bond angles of that particular compound. For example, considering the molecule of water, we already know that it is a polar molecule with partially positive hydrogen atoms and partially negative oxygen atoms and acts as universal solvent. The bond angle in water is about 104.5° with a Bent geometry. Unlike carbon dioxide (CO₂) which has Linear structure with bond angle 180° and is non-polar in nature therefore, the bent geometry in water is responsible for the polarity.
Other properties which can also be predicted by predicting the bond angles along with molecular geometries are;
i) Magnetism
ii) Phase of matter
iii) Color
iv) Reactivity
v) Biological activities <em>e.t.c</em>
