When an acetylene torch is used to weld metal an exothermic reaction occurs. which is the balanced chemical equation for this reaction?

a. 2c2h2(g) + o2(g) → co2(g) + 2h2o(g) + energy

b. 2c2h2(g) + o2(g) → 4co2(g) + h2o(g) + energy

c. 2c2h2(g) + 5o2(g) → 4co2(g) + 2h2o(g) + energy

d. c2h2(g) + 5o2(g) → 4co2(g) + 2h2o(g) + energy

Wo audio speakers are placed on a vertical rail. speaker a is placed at head-level while speaker b is place at some variable height, \delta yδy, above speaker a. both speakers receive simultaneous input from a sine-wave generator so the speakers each produce a pure sinusoidal sound wave with a wavelength of 0.531 meters. calculate the lowest height that speaker b can be placed above speaker a to produce a minimum of sound heard by person standing \delta x = 7.86δx=7.86 meters directly in front of speaker a.

Apackage of supplies is dropped from a plane, and one second later a second package is dropped. neglecting air resistance, the relative velocity of the 1st package viewed from the second will 56) a) increase. b) be constant. c) be zero. d) depend upon their weight. e) decrease

Laboratory experiments, observational field studies, and model-building are all examples of different forms of scientific investigations.  in what way do laboratory experiments primarily differ from other forms of scientific investigations?   a.  a laboratory experiment is the only accepted form of investigation within the scientific community.  b.  studies about how things behave in nature or studies involving very large objects are best answered through laboratory experiments.  c.  laboratory experiments involve the identification and control of variables.  d.  data can only be generated through laboratory experiments, not other forms of investigation.