Answer:
It has no shape of its own but has a definite volume.
Explanation:
Gases have no shape but a definite volume
 
        
                    
             
        
        
        
Answer:
The shadow will appear dark
Explanation:
Your shadow is caused by your body blocking incident light rays from reach the ground under the shadow area. The absence of light means there will be no light reflected from the ground making it appear dark. 
 
        
             
        
        
        
Answer:
 All the given option is false.
Explanation:
A)
This is not true for all the materials like composite because the Poisson ratio for composite material can be negative that is why positive tensile stress may produce positive lateral strain.
B)
This is not true for all the material because the Poisson ratio for some material can be positive  that is why positive tensile stress may produce negative lateral strain.
C)
The explanation is same as option A.
D)
This is not true for all the materials ,It is valid only up to elastic limit .After the elastic limit the strain and stress does not follow linear path.
E)
This is not true for all the materials because some materials like composite is having negative value of Young's modulus.
Therefore all the given option is false.
 
        
             
        
        
        
Answer: to achieve a stable octet of electrons in their outer shell
Explanation:
- Sodium (Na) has an atomic number of 11, and an electronic configuration of 1s2, 2s2 2p6, 3s1. 
- Chlorine (CI) Sodium (Na) has an atomic number of 17, and an electronic configuration of 1s2, 2s2 2p6, 3s2 3p5. 
Hence, sodium donates its single valence electron to chlorine, thereby achieving a stable octet structure of 1s2, 2s2 2p6 while chlorine accept the single electron also forming a stable octet structure of 1s2, 2s2 2p6, 3s2 3p6. Therefore, the reaction yields NaCl, an ionic compound with ionic (electrovalent) bond. 
Na + Cl --> NaCl
Thus, Sodium(Na) and Chlorine (CI) want to form a lonic Bond because both acheive a completely filled outermost shell (octet structure)
 
        
             
        
        
        
The object rises to a height of 20.4 m. So option C  is correct.
Explanation:
initial velocity= Vi=20 m/s
final velocity at the top= Vf=0
acceleration= g=-9.8 m/s²
Vf²=Vi²+2gh
0= (20)²+2 (-9.8)h
-200=-9.8h
h=200/9.8
h=20.4 m
Thus the object rises to a height of 20.4 m