Answer:
Pre-zygotic, temporal separation
Explanation:
Reproductive isolation mechanism is of two types:
- Prezygotic mechanism
- Postzygotic mechanism
Prezygotic mechanism isolation occurs before fertilization and helpful in preventing formation of fertile offspring.
In frog external fertilization occurs. In the external fertilization, eggs and sperms are released in water and fertilization occur outside the water.
Prezygotic isolating mechanisms may include behavioral isolation, temporal isolation, mechanical isolation, gametic isolation and habitat isolation.
Temporal separation in reproduction is the sexual activity in the same geographical range but in different periods.
Therefore, the given reproductive isolation is pre-zygotic, temporal separation.
Answer:
Elements having same valence electrons are placed in <u>same group.</u>
Explanation:
First, let's start with some basic concepts of modern periodic table:
1. Modern Periodic table : It is the arrangement of element in the increasing order of their atomic numbers
The Modern periodic table is divided into Periods and groups .
Periods : These are the horizontal rows. There are seven periods in the periodic table . Period 1 has 2 element. Period two and three has 8 elements , period 4 and 5 have 18 elements and the period 6 and 7 have 32 elements.
Same period have same number of atomic orbital(Shell)
Group : The group is the vertical columns . There are 18 groups in the modern periodic table.Those element which have same group number will also have same number of electron in their outermost shell. The number of electron in the outermost shell determines the valency of the element.
So, elements showing same valency are placed in same group.
All alkali are place in group 1 and have 1 valance electron in the outermost shell
Answer:
Au
Explanation:
For the density of a face-centered cubic:

where
= molar mass of the compound
avogadro's constant
the volume of a unit cell
Given that:
Density
= 19.30 g/cm³
a = 0.408 nm
a = 
a = 
∴



Thus, the molar mass of 197.37 g/mol element is Gold (Au).