Answer:
0.8 g/cm^3
Explanation:
Density is the amount of substance present per volume.
Density = Mass / Volume = (25.0 g) / (30.0 cm) = 0.83333 g/cm^3
=> Density = 0.8 g/cm^3 (rounded up to one decimal place)
Answer:
Elements in the same group of the periodic table have the same number of valence electrons. These are the electrons in their outer energy level that can be involved in chemical reactions. ... All the elements in group 1 have just one valence electron. This makes them very reactive.
Explanation:
The pH of the solution at 25 degree celsius of 1.3 × 10⁻⁶ moles of a sample of Sr(OH)₂ is 10.02.
<h3>How do we calculate pH?</h3>
The pH of any solution gives an idea about the acidic and basic nature of the solution and the equation of pH will be represented as:
pH + pOH = 14
Given that,
Moles of Sr(OH)₂ = 1.3 × 10⁻⁶ mol
Volume of solution = 25mL = 0.025L
The concentration of Sr(OH)₂ in terms of molarity = 1.3×10⁻⁶/0.025
= 5.2×10¯⁵M
Dissociation of Sr(OH)₂ takes place as:
Sr(OH)₂ → Sr²⁺ + 2OH⁻
From the stoichiometry of the reaction 1 mole of Sr(OH)₂ produces 2 moles of OH⁻.
Given that the base is a strong base and that it entirely dissociates into its ions, the hydroxide ion concentration is 5.2×10¯⁵×2 = 1.04×10¯⁴ M.
pOH = -log[OH⁻]
pOH = -log(1.04×10¯⁴)
pOH = 3.98
Now we put this value on the first equation we get,
pH = 14 - 3.98 = 10.02
Therefore, the value of pOH is 10.02.
Learn more about pH here:
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The electrical charge of an atom having 15 proton, 14 neutrons and 16 electrons is -1. The correct option is D.
What is an atom?
An atom is the smallest unit of any matter which comprises of central nucleus and electrons revolving around the nucleus in definite energy shells. The atom is made up of protons, neutrons and electrons.
The electrical charge of an atom can be calculated as,
Charge of an atom = number of protons - number of electrons
Charge = 15 - 16 = -1.
The neutrons are neutral and do not contribute to the charge, the protons are positively charged and electrons are negatively charged in an atom.
Therefore, the charge of an atom with 15 protons, 14 neutrons and 16 electrons is -1. The correct answer is option D.
To learn more about atom click on the given link brainly.com/question/6258301
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Earthquakes make the surface all cracky and hard where it’s hard to dig up and the soil is like hard to step on because one false move and you could fall down
