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Answer:
1M HCl: add 1mol/12M = 83 ml conc. HCl to 1L of water or 8.3ml to 100ml.
2M HCl: add 2mol/12M = 167 ml conc. HCl to 1L of water or 16.7ml to 100ml.
Given the choices;
a) Bourdon gauge flowmeter
b) Hudson gauge flow meter
c) Constant flow selector
d) pressure compensated flowmeter.
The one that can only be used upright is the pressure-compensated flowmeter. Compensated flowmeters work with a variable orifice and fixed pressure. They read back pressure, and take into account resistance changes down stream from the needle valve. If pressure exceeds 50psig downstream, flow ceases.