Science

An atomic model shows 19 protons, 20 neutrons, and 19 electrons. What is the mass number of the atom?(1 point)

39
58
19
20
I need help

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  1. Me. To

    Does any one have the answers to that test????
    Help me pleas!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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  2. Oh I think the first one is 39. That al I got

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  3. An atomic model shows 19 protons, 20 neutrons, and 19 electrons. What is the mass number of the atom?(1 point)
    39
    58
    19
    20

    To create a molecular model, a student will use blue spheres to represent nitrogen (N) and white spheres to represent hydrogen (H). Which option correctly describes a model of ammonia, NH3?(1 point)

    three blue spheres and one white sphere
    three blue spheres and three white spheres
    one blue sphere and three white spheres
    one blue sphere and one white sphere

    A ball-and-stick model of a molecule of formaldehyde, CH2O, is made from the following components:

    one black ball
    one red ball
    two white balls
    three sticks
    What do the sticks represent?

    (1 point)

    oxygen atoms
    bonds between atoms
    hydrogen atoms
    carbon atoms

    Potassium and nickel are in the same row of the periodic table. What do these elements have in common?(1 point)

    They have similar physical properties.
    They have similar reactivity.
    They have the same number of valence electrons.
    They have the same number of electron shells.

    Why do elements that are in the same group of the periodic table share similar properties?(1 point)

    They all have the same number of electrons in the outer shell.
    They are all very reactive with other elements.
    They all have the same atomic mass.
    They are all metals.

    Which option is an example of a chemical change?(1 point)

    slicing an apple
    ripping paper into pieces
    boiling water
    baking a cake

    A scientist is using a lithium ion battery to power her laptop. Which statement about the battery is correct?(1 point)

    The mass of the battery increases when it is recharged.
    A new substance is formed as the battery is used.
    Electrons are lost to the environment when the battery is used.
    Lithium atoms are created as the battery recharges.

    Use the chemical reaction to answer the question.

    2H2O2→2H2O +O2
    2
    H
    2
    O
    2

    2
    H
    2
    O

    +
    O
    2

    Which statement about the reaction is correct?

    (1 point)

    H2O and O2 have the same mass as H2O2.
    Atoms of H2 and O2 are lost during the reaction.
    The reaction creates new atoms of H2O and O2.
    H2O2 has the same properties as H2O and O2.

    Suppose 20 atoms of hydrogen (H) react with chlorine (Cl) to produce 20 molecules of hydrochloric acid (HCl). According to the Law of Conservation of Matter, how many atoms of chlorine reacted with the hydrogen?(1 point)

    40
    20
    10
    0

    What does it mean for a chemical equation to be balanced?(1 point)

    It has the same type of molecules on both sides.
    It has the same number of molecules on both sides.
    It has the same type of atoms on both sides.
    It has the same number of atoms of each element on both sides.

    How many atoms are represented in the formula Na2HPO4?(1 point)

    nine
    six
    four
    eight

    I need help to !!!!!!!!!!!

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  4. I don't do complete tests. The mass number is 39 for the first one.

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    👤
    DrBob222
  5. This is chaos I am gonna look for answers somewhere else LOL

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  6. @GoofyProduct
    there not anywhere else smh i give up

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  7. I completed it 100% (also girl in red notice me!!😭)
    1. 39
    2. 9 E, 9 P, 10 N
    3. 1 blue sphere 3 white spheres
    4. Bonds between atoms
    5. They have the same number of electron shells
    6. Atomic orbital
    7. Protons repel the particles, while neutrons do not.
    8. Alkali metals
    9. Arsenic
    10. Number of orbitals
    11. Silcon and germanium
    12. The tendency of an atom to attract electrons in a bond
    13. It forms covalent bonds because it wants four more electrons to share in order to fill its outer shell
    14. 3-
    15. It has a half-full outer shell of electrons, allowing it tl form a wide variety of bonds.
    16.methyl

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  8. Yall don't read it says it doesn't count as a grade but a I think boy in blue has it down

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  9. Yk you can check your answer as you go right

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  10. @ Boy In Blue, Ty so much!

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  11. the first few(1-5) were right for me but then the rest weren't even options

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  12. When would you have taken the test fellow class mate

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  13. yall it has check anser you should get it right.

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