Answer:
he predicted the properties from known elements above and belws the unknown in the same group
Explanation:
What allowed Mendeleev to make predictions of undiscovered elements
He realized that an element on this table with one known element above it and one known element below it had to have properties between the two known elements
How did Mendeleev predict gallium and germanium?
Based on gaps in the periodic table Mendeleev deduced that in these gaps belonged elements yet to be discovered. Based on other elements below and above in the same group he predicted the existence of eka-aluminum, eka-boron, and eka-silicon, later to be named gallium (Ga), scandium (Sc), and germanium (Ge).
Answer:
OD. 2HCl
Explanation:
A balanced equation needs the equal # of each element on BOTH sides.
By putting a 2 in front of HCl you now have 2 hydrogens on both sides and 2 chlorines. The Ca and CO3 are already balanced.
Answer:
Check the electronic configuration of elements.
Explanation:
▪Valence electrons are the elwctrons present in the outermost shell of any element.
For example,
Electronic Configuration of Sodium = 2,8,1
Here , Sodium has 1 valence electrons.
▪Valency of an element is the total no. of electrons to be gained/losed in order to achieve duplet/octate state.
For example,
Electronic configuration of Sodium = 2,8,1
Sodium can achieve octate state either by losing 1 electron or gaining 7 electrons. But losing 1 electron is eay than gaining 7 electrons. So Valency of Sodium = +1
☆Metals have 1 or 2 or 3 valence electrons.
☆Non metals have 4 or 5 or 6 or 7 valence electrons.
☆Noble gases tend to stay in duplet/octate state i.e they have 2 or 8 valence electrons.
The type of reaction that occurs without the addition of heat is called spontaneous reaction. That is option D.
<h3>What is spontaneous reaction?</h3>
Spontaneous reaction is defined as the reaction where by new substances are formed naturally without the addition of extra energy in the form of heat.
Therefore, the type of reaction that occurs without the addition of heat is called spontaneous reaction
Learn more about heat here:
brainly.com/question/13439286
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Answer:
B. Cell Type
Explanation:
that is the answer i believe
