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3 years ago

Give the number of significant figures in this number: 7.8 x 10¹²

1 answer:

8 0

The number is written in scientific notation.

The significant figures are the numbers known precisely plus 1 digit that is uncertain.

When the numbers are expressed in scientific notation all the digits before 10^n are significant.

So, 7 and 8 are significant figures and the answer is that the number of significant figures is 2.

Answer: 2

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Physical Meaning of pKa Which of the following aqueous solutions has the lowest pH: 0.1 M HCl; 0.1 M acetic acid (pKa = 4.86); 0

ser-zykov [4K]

Answer:

The solution with the lowest pH is 0.1 M HCl.

Explanation:

Since the three solutions have the same concentration (0,1M) it is only necessary to look at the pKa of each solution.

Also, knowing that a higher pKa means a lower Ka, because pKa = -Log (Ka). Thus, a lower Ka means a lower concentration of protons with a higher pH ( pH = -Log [H+].

The HCl doesn't have a pKa because is a strong acid that dissociates completely. Therefore, this solution produces a lower pH. Looking at the pKa of acetic acid and formic acid solutions, the second with the lowest pH is the formic acid solutions and the higher pH is for the acetic acid solution.

3 0

3 years ago

fictitious element Jz has two common isotopes. Three-fifth of the isotopes have a mass of 329.1 amu, while the rest have a mass

Alla [95]

The average atomic mass of Jz is 331.3 u.

The average atomic mass of Jz is the weighted average of the atomic masses of its isotopes.

We multiply the atomic mass of each isotope by a number representing its relative importance (i.e., its fractional abundance).

Thus,

⅗ × 329.1 u = 197.46 u

⅖ × 334.5 u = 133.80 u

TOTAL = 331.3 u

7 0

2 years ago

Zeros that act as are not significant

GaryK [48]

Explanation:

non zeores digits always significant any zero between two significant digits are significant a final zeros in the decimal portion only are significant

6 0

2 years ago

5. Which are forms of energy? Select all that apply.

slavikrds [6]

Answer:

There are mechanical energies. These consist of kinetic energy and gravitational potential energy.

Kinetic energy is the energy an object contains when it is in motion. Ex.: A car moving, a ball falling off of a building.

Gravitational potential energy is the potential for an object to do work at a certain height. If a 1 kg ball is placed 1 meter high, it has 9.8 Joules of potential energy, represented with the equation, Ug=mgh.

There are Non-Mechical Energies, which I assume you are trying to get. There is Thermal Energy, Electrical Energy, Light, Sound, Nuclear Energy, and Chemical Energy.

Thermal Energy is essentially heat. Friction causes thermal energy.

Electrical energy is potential difference. It is the work that can be done by a point charge.

Nuclear energy is like fission and fusion

Chemical energy is energy from chemical processses. Think, photosynthesis for example.

Sound is molecules hitting other molecules. It occurs a lot with friction as well.

Light is, well, you know what light is.

Explanation:

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4 0

2 years ago

Buckminsterfullerene is an allotrope of carbon that is found in:

jarptica [38.1K]

Bucky balls, or bucksminsterfullerene, can be found in Soot in small quantities.

3 0

2 years ago