Answer: C) rare earth elements are in the first column, on the left.
Explanation:
In fact, rare earth elements are in the third column, on the left.
The periodic table of the elements is an arrangement of the chemical elements in the form of a table, ordered by their atomic number (number of protons), by their configuration of electrons and their chemical properties. It was progressively developed over time as the scientific knowledge advanced; for this reason many modifications and corrections might be done in the future.
This table is divided into rows and columns, which represent the periods and groups or families. For its location the atomic number and valence of each element was considered.
In this sense, the elements in the periodic table are mainly arranged as follows:
-Alkali metals and Alkaline Earth metals in the first two columns, on the left.
-Rare earth elements in the third column (rows 6 and 7), on the left.
-Transition metals in the center.
-Basic metals and semi-metals to the right
-Non-metals to the right (and Hidrogen in the first row and column)
-Noble gases (or inert gases) farthest to the right.
Answer: The correct answer is Option C.
Explanation:
Elements are divided into 7 Periods and 18 Groups in a periodic table.
Metals are present on the left side of the periodic table. They are present from Group 1 to Group 14 of the periodic table.
Non-metals are present on right side of the periodic table. They are present from group 15 to group 17 of the periodic table.
Inert gases are present in the farthermost right side of the periodic table. They are present in group 18.
Transition metals are present in the center of the periodic table from group 3 to group 12.
Rare earth metals are present in group 3 from the left. All the elements present in lanthanides series are considered as rare Earth metals.
Hence, the correct answer is Option C.
When the number of electron and number of protons are equal in the atom then the atom is said to be an electrically neutral atom. The loss of electron will result in the formation of cation and the atom will possess positive charge which is equal to the number of electrons lost whereas the gain of electron will result in the formation of anion and the atom will possess negative charge which is equal to the number of electrons gained.
The electrically neutral atom have 0 charge as the number of protons and electrons are equal.
For electrically neutral atom of hydrogen, the number of electron =1 and the number of proton = 1.
Hence, the charge on an electrically neutral atom of hydrogen is 0.
Its B zero because its neutral meaning that there balance
(2) 19 protons and 42 neutrons
(3) 20 protons and 19 neutrons
(4) 23 protons and 19 neutrons
Natural systems like water in a pond rarely reach thermal equilibrium due to temperature differences and energy transfer limitations.
Natural systems like the water in a pond rarely reach thermal equilibrium due to various factors.
These factors prevent the pond from reaching thermal equilibrium.
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Answer: -7.5
Explanation: To solve for y in the equation -3/(y + 6) = 2, you can follow these steps:
First, we want to get rid of the fraction. To do that, multiply both sides of the equation by (y + 6) to cancel out the denominator:
-3/(y + 6) * (y + 6) = 2 * (y + 6)
This simplifies to:
-3 = 2(y + 6)
Now, distribute 2 on the right side of the equation:
-3 = 2y + 12
Next, isolate the term with 'y' by subtracting 12 from both sides of the equation:
-3 - 12 = 2y
-15 = 2y
Finally, divide both sides by 2 to solve for 'y':
-15/2 = y
So, the solution for y is:
y = -15/2
You can also express this as a mixed number:
y = -7.5