In 1871, a Russian Chemist, Dimitri Mendeleev, gave a useful scheme for classification of elements. He presented the first regular periodic table in which elements of similar chemical properties were arranged in eight vertical columns called groups. The horizontal rows of table were called periods. He arranged elements in ascending order of their atomic masses and found that elements having similar chemical properties appeared at regular intervals. This observation was called Periodic Law.
C: One plate is going underneath the other plate and sinking into the soft rock below.
Explanation:
Where plates are moving towards each other they are said to converging, and are called convergent margins.
The lithosphere is broken into series of slabs called plates. The plates moves on the weak and relatively soft asthenosphere below.
Plates have different motion. At some places, they move apart and they are said to be divergent.
When plates moves towards each other, they are convergent. At a convergent margin, a plate collides with another thereby causing the denser plate usually the oceanic plate to subduct into the asthenosphere. In some other cases, the plates can collide and build upward.
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Answer:
Periods have consecutive atomic number as they are in a row and groups are vertical meaning they are in a column and groups have similar properties
Answer:
The percent by mass of water in this crystal is:
Explanation:
This exercise can be easily solved using a simple rule of three where the initial weight of the hydrated crystal (6,235 g) is taken into account as 100% of the mass, and the percentage to which the mass of 4.90 g corresponds (after getting warm). First, the values and unknown variable are established:
- 6,235 g = 100%
- 4.90 g = X
And the value of the variable X is found:
- X = (4.90 g * 100%) / 6,235 g
- X = approximately 78.6%.
The calculated value is not yet the percentage of the water, since the water after heating the glass has evaporated, therefore, the remaining percentage must be taken, which can be calculated by subtraction:
- Water percentage = Total percentage - Percentage after heating.
- <u>Water percentage = 100% - 78.6% = 21.4%</u>
Answer is: pH value of weak is 3.35.
Chemical reaction (dissociation): HA(aq) → H⁺(aq) + A⁻(aq).
c(HA) = 0.0055 M.
α = 8.2% ÷ 100% = 0.082.
[H⁺] = c(HA) · α.
[H⁺] = 0.0055 M · 0.082.
[H⁺] = 0.000451 M.
pH = -log[H⁺].
pH = -log(0.000451 M).
pH = 3.35.
pH (potential of
hydrogen) is a numeric scale used to specify the acidity or basicity <span>an aqueous solution.</span>
