1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Bond [772]
3 years ago
14

The distance to nearby stars can be measured by using ?

Chemistry
1 answer:
BigorU [14]3 years ago
8 0

Nearby stars are measured with parallax, which involves two measurements of the star's exact position in the sky.

Hope this helped!

Good luck :p

Brainliest is appreciated <3

~ Emmy

You might be interested in
or a particular isomer of C 8 H 18 , the combustion reaction produces 5104.1 kJ of heat per mole of C 8 H 18 ( g ) consumed, und
beks73 [17]

Answer:

The standard enthalpy of formation of this isomer of C_{8}H_{18} is -220.1 kJ/mol.

Explanation:

The given chemical reaction is as follows.

C_{8}H_{18}(g)+ \frac{25}{2}O_{2}(g) \rightarrow 8CO_{2}(g)+9H_{2}O(g)

\Delta H^{o}_{rxn}= -5104.1kJ/mol

The expression for the entropy change for the reaction is as follows.

\Delta H^{o}_{rxn}=[8\Delta H^{o}_{f}(CO_{2}) +9\Delta H^{o}_{f}(H_{2}O)]-[\Delta H^{o}_{f}(C_{8}H_{18})+ \frac{25}{2}\Delta H^{o}_{f}(O_{2})]

\Delta H^{o}_{f}(H_{2}O)= -241.8kJ/mol

\Delta H^{o}_{f}(CO_{2})= -393.5kJ/mol

\Delta H^{o}_{f}(O_{2})= 0kJ/mol

Substitute the all values in the entropy change expression.

-5104.1kJ/mol=[8(-393.5)+9(-241.8)kJ/mol]-[\Delta H^{o}_{f}(C_{8}H_{18})+ \frac{25}{2}(0)kJ/mol]

-5104.1kJ/mol=-5324.2kJ/mol -\Delta H^{o}_{f}(C_{8}H_{18})

\Delta H^{o}_{f}(C_{8}H_{18}) =-5324.2kJ/mol +5104.1kJ/mol

=-220.1kJ/mol

Therefore, The standard enthalpy of formation of this isomer of C_{8}H_{18} is -220.1 kJ/mol.

4 0
3 years ago
Identify the ion ratios needed to form neutral compounds from the ions below. The metal ion (cation) is listed first, and the no
Natasha2012 [34]
To figure out the ratios of these compounds, it is important to remember that the charge of these compounds must be <em>neutral</em>.

So in order to make them neutral, you must have specific ratios:

Na^{+}: Br^{-}  =1:1; This is true because they both have a charge of magnitude of 1.

Al^{3+}: Cl^{-}=1:3; We need 3 chlorine atoms because we need to balance out the charge from the 3+ charge of aluminum - therefore since chlorine has a 1- charge, we need 3 atoms.

Mg^{2+}: O^{2-}=1:1; The charges of the magnesium (2+) are balanced with the oxygen charge (2-).

Al^{3+}: O^{2-}=2:3; This is correct because if charges are like this, you must find the least common factor in order to know the ratio. The LCF is 6, therefore, for the atom with a 3+ charge, you need 2 of them, and for the atom with a 2- charge, you need 3 of them. This keeps the charge neutral.

7 0
3 years ago
Read 2 more answers
*Fill in the blank about the periodic table*
Anastaziya [24]

Atomic number equals the number of protons or electrons. Atomic mass equals the number of protons and neutrons

7 0
3 years ago
8. Based on the formula, predict whether each of the following compounds is primarily ionic or primarily covalent. a. sodium iod
Lina20 [59]

primarily ionic  include = sodium iodide( NaI) ,   calcium chloride  ( CaCl2)


primarily covalent    include  - Ammonia (NH3) , Methane ( CH4)  and  

                                                   Glucose  (C6H12O6)


Explanation

ionic  bond  is formed  when  there is complete transfer of electron between atoms. It occur  between metal  which  donate electrons and  a  non  metal which accept  electrons.

 for  example  in  formation  of CaCl2,   ca  donate  2 electron to 2  Cl atom, while  2 Cl atom accept the 2  electrons  to form ionic bond.

 Covalent bond  is formed  when two or  more  non  metal  form bond by sharing  electrons pairs.

For  example in NH3   3 pairs of electron are shared.  to form covalent bond.

                               

8 0
3 years ago
If the symbol X represents a central atom, Y represents outer atoms, and Z represents lone pairs on the central atom, the struct
Snowcat [4.5K]

Answer:

XY4Z2 ----- square planar

XY5Z ------- square pyramidal

XY2Z----- bent < 120°

XY2Z3 ----- Linear

XY4Z ---- see saw

XY2Z2 ----- bent <109°

XY3Z2 ----- T shaped

XY3Z ----- Trigonal pyramidal

Explanation:

The valence shell electron pair repulsion theory ( VSEPR) gives the description of molecular geometry based on the relative number of electron pairs present in the molecule.

However, electron pairs repel each other, the repulsion between two lone pairs is greater than the repulsion between a lone pair and a bond pair which is also greater than the repulsion between two lone pairs.

The presence of lone pairs distort the bond angle and molecular geometry from the expected geometry based on VSEPR theory. Hence, in the presence of lone pairs of electron, the observed molecular geometry may be different from that predicted on the basis of the VSEPR theory, the bond angles also differ slightly or widely depending on the number of lone pairs present.

All the molecules in the question possess lone pairs, the number of electron pairs do not correspond to the observed molecular shape or geometry due to lone pair repulsion. Usually, the molecular geometry deals more with the arrangement of bonded atoms in the molecule.

8 0
4 years ago
Other questions:
  • A 30.7 g sample of Strontium nitrate, Sr(NO3)2•nH2O, is heated to a constant mass of 22.9 g. Calculate the hydration number.
    11·2 answers
  • If a person looking at a poster sees green instead of yellow and doesn't see red at all, this person most likely has color blind
    5·2 answers
  • A sample of glass bead weighs 34.5g. The beads are heated to 100.0C in a boiling water bath and poured into a beaker containing
    11·1 answer
  • The empirical formula for a compound is CH2O, and the molar mass is 180.2 g/mol. Which is the molecular formula for this compoun
    7·1 answer
  • Which of the following is an elastic force
    6·1 answer
  • Why are the terrestrial planets closest to the sun while the gas planets are farther from the sun?
    14·1 answer
  • What is Avogadro's number?
    14·1 answer
  • Provide one example of how life on Earth would not be possible without water based on its characteristics.
    9·1 answer
  • What is the density of an object whose mass is 120 grams and whose volume is 60 cm3? (D=m/v)
    15·2 answers
  • Biochemistry which studies the chemical composition, structure, and the reaction of compounds found in non-living organisms.
    5·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!