Explanation:The tetrahedral shape is formed by the electrons repulsing one another, which forms the tetrahedron—the shape in which all the electrons are as far away from one another as possible.
Examples include methane (CH4) and ammonium(NH4+).
Methane has a central carbon atom ringed by four hydrogens, which form the "spokes" of the tetrahedral molecule.
Tetrahedral molecules are nonpolar if the four surrounding atoms are the same, in the cases of methane and ammonium, and have a bond angle of 109.5˚.
However, tetrahedral molecules can also be polar if they are like chloroform (CHCl3). The central atom has four electron domains, but they are differently sized.
<span>Agar
is known to be a gelatinous polymer substance that was commonly used in the
laboratory setting as a substrate. Thus, nutrients agar can grow different types
of microbes such as fungi and bacteria while MacConkey agar is made with bile
salts and crystal violets, these additives cause the agar to only grow Gram –
negative bacteria. However, nutrients agars grow more organisms because it
contains nutrients from either beef broth or yeast extracts when compared with MacConkey
agar.</span>
Answer:
C. Both (a) and (b)
Explanation:
Hunting, destroying habitats, polluting and introducing non-native species can cause extinction.
Answer:
Due to mixing of particles present in the upper layer of limestone with sandstone during deposition.
Explanation:
The parent layer was limestone layer which is older than sandstone layer. This sandstone layer spreads on the limestone layer because of wind. The wind moves these sandstone from other region and their deposition occurs on the limestone layer. During deposition of sandstone, some particles of limestone which are present at the surface mixes with the sandstone so that's why in sandstone layer, small and weathered pieces of limestone are present.
