A(n) ____________ is a substance in which all the exact combinations of elements are always the same.a.synthetic element
b.compound
c.mixtures
d.solution
Answers
A compound is a substance in which all the exact combinations of elements are always the same. The correct option is b.
What is a compound?
Compounds are substances that are made up of two or more substances or elements. A compound is a mixture of two elements, they share bonds with each other, and they form a totally different substance than the above elements.
For example, NaCl is a compound. It is formed by two elements, sodium, and chloride. These elements form a different compound that is common table salt.
Some compounds are pure substances because they are made up of only elements that mix together. They do not contain any impurity or any other substance. They share chemical bonds with each other.
Thus, the correct option is b. compound.
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source is Glencoe Science book grade 7.
Also I just happening to be learning about this at school
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In this equation, what should be the coefficients of the reactants and products? I2 + O2 → I4O9
What is the chemical equation of ccl4, please explain thank you! :-D
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The mass of 4.35 ×10⁶ atoms of carbon-12 atom is 8.668×10 g.
What is a mole ?
A mole is a standard specific unit prescribed for measuring large quantities of entities which are very small such as atoms, molecules.It represents large number of units that is 6.022×10²³.
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Concept of mole provides quantitative information as to what happens in chemical reaction at a macroscopic level.It is used for determination of simplest formula of a compound.
For all practical purposes, mass of one mole of compound in grams is approximately equal to mass of one molecule of compound measured in Daltons.
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Answers
Answer : The temperature on the Kelvin scale is, 373 K
Solution :
As temperature is given . Now we have to determine the temperature in Kelvin scale.
Formula used :
K = temperature in kelvin = ?
= temperature in degree Celsius =
Now put the value of 'K' in the above formula, we get the temperature in kelvin scale.
Therefore, the temperature on the Kelvin scale is, 373 K
Answers
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant.
(1) Group 1, Period 4 (3) Group 2, Period 3
(2) Group 2, Period 5 (4) Group 3, Period 4
Answers
Answer: Option (2) is the correct answer.
Explanation:
Ionization energy is defined as the energy required to remove the most loosely bound electron from a neutral gaseous atom.
And, when we move across a period then there is a decrease in the ionization energy due to decrease in the size of atoms.
Whereas when we move down a group then there is an increase in ionization energy because of increase in size of the atoms.
Since, it is given that each atom has 2 valence electrons therefore, all the atoms belong to group 2.
And, as it has lower first ionization energy than calcium it means the atom is larger in size than calcium atom.
Hence, we can conclude that this element located in Group 2, Period 5 on the periodic table.
Final answer:
The element with two valence electrons and a first ionization energy lower than calcium would be found in Group 2, Period 5 on the Periodic Table.
Explanation:
The element you're referring to, with two valence electrons and a lower first ionization energy than calcium, would be located in Group 2, Period 5 on the Periodic Table.
Here's why: Group 2 elements, or alkaline earth metals, all have two valence electrons. Periods on the other hand, describe the energy level of an atom's outermost electrons, with higher periods corresponding to higher energy levels. Thus, an atom in a higher period would have a lower ionization energy (the energy required to remove an electron) than one in a lower period.
Therefore, because the first ionization energy is lower than calcium (which is in Group 2, Period 4) but still has two valence electrons, this element would be located one period below, in Group 2, Period 5.
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Answers
According to periodic trends, bismuth has the greatest atomic radius.