Answer:
Modern periodic table has eighteen (18) vertical columns. These are called groups
Answer:
Mass of ammonia = 34 g
Explanation:
Given data:
Number of molecules of ammonia = 1.204 × 10²⁴
Mass of ammonia = ?
Solution:
First of all we will calculate the number of moles.
one mole of ammonia = 6.022 × 10²³ molecules
n = 1 mole/6.022 × 10²³ molecules × 1.204 × 10²⁴ molecules
Number of moles = 2 mol
Mass of ammonia:
Number of moles = Mass / molar mass
Mass of ammonia = number of moles × molar mass
Mass of ammonia = 2 mol × 17 g/mol
Mass of ammonia = 34 g
Here are the key events listed in chronological order with
their corresponding year.
1. Hooke coins the word cell after viewing cork cells with
primitive microscope. (1665)
2. van Leeuwenhoek discovers bacteria with his improved
microscope. (1676)
3. Brown recognizes and names the cell nucleus. (1831)
4. Schleiden & Schwann propose cell theory. (1839)
5. Virchow describes cell division; proposes that all cells
arise from other cells. (1855)
<span>6. Pasteur disproves spontaneous generation and proposes germ
theory. (1861)</span>
Answer:
true
Explanation:
because Lewis represent valid resonance