Answer:
Mendeleev had left the noble gases out of his periodic table.
Explanation:
Mendeleev's periodic table is pictured in the image attached to the question.
Mendeleev's table obviously lacked the noble gases. The reason for this grave omission is simple; the noble gases were not known as at the time when he formulated his periodic table. There weren't any known elements whose properties were similar to the properties of the noble gases. This would have lead him to suspect their existence.
Answer:
quartz (SiO2)n
Explanation:
Melting point is defined as the temperature or point at which the substances change its state from solid to liquid.
Quartz (SiO2)n has high melting point than O2 because Quartz (SiO2)n is found in the form of hard, crystalline mineral that is made up of silicon and oxygen atoms having strong covalent bonds between all the atoms. So, a lot of energy is required to break the bond between the atoms and it has a high melting point.
Hence, the correct answer is quartz (SiO2)n.
Here are the choices:
Warm air rises while cold air falls.
The warmer air contains less water vapor per unit of volume.
The warmer air contains more water vapor per unit of volume.
Moist air has lower density than dry air does.
The best answer is: <em>The warmer air contains more water vapor per unit of volume.
</em>
multiply the number of each atom with its molecular mass. (see the periodic table)
5*12 + 12*1 = 72 gram per mole.
Or more accurately: 5*12.01078 + 12*1.007947 = 72.149264 g/mole
The density of a solid object that has a mass of 1.62 lb and a volume of 190 mL is 3.87g/mL.
<h3>How to calculate density?</h3>
Density is the measure of the mass of matter contained by a unit volume. It can be calculated by dividing the mass of the substance by its volume.
According to this question, a solid object is said to have a mass of 1.62 lb and a volume of 190 mL.
1 pound = 453.592 grams
1.62 Ibs is equivalent to 734.82 grams
Density of the solid object = 734.82 grams ÷ 190 mL
Density = 3.87g/mL
Therefore, the density of a solid object that has a mass of 1.62 lb and a volume of 190 mL is 3.87g/mL.
Learn more density at: brainly.com/question/20337365
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